spring 3.2 configuration tx:annotation-driven error in eclipse - spring

Question

Trying to migrate from Spring 3.0 -> 3.2.4
using: Eclipse Juno (on 64 bit java 1.7), and STS 3.3,
Problem: Edit window in Eclipse/STS IDE shows:
Error occurred processing XML
'org/springframework/aop/config/AopNamespaceUtils'
on the line where I am using <tx:annotation-driven>
Compiling the project results in a similar error.
java.lang.NoClassDefFoundError: org/springframework/aop/config/AopNamespaceUtils
I've been struggling to find a resolution to this. I'm assuming that it's something simple I've overlooked, but I can't for the life of me find it.
Here's what I've done so far:
I've created the config file from scratch using Eclipse -> new file
-> STS bean configuration.
I've confirmed that maven has installed the appropriate jars into
the classpath.
I've compiled with both java versions 1.6 and 1.7
started eclipse with -clean (in case there were any artifacts left by older project and workspace versions)
<tx:annotation-driven> was added using the normal Eclipse ctrl+space
explicitly added spring-web to pom.xml (Spring version 3.2 removed the required dependency, but it made no difference, in or out)
explicitly added spring-aop to pom.xml
Any help or insights would be appreciated.
Here is my config-portlets.xml (prior version of this worked in Spring 3.0)
<?xml version="1.0" encoding="UTF-8"?>
<beans xmlns="http://www.springframework.org/schema/beans"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:context="http://www.springframework.org/schema/context"
xmlns:mvc="http://www.springframework.org/schema/mvc" xmlns:p="http://www.springframework.org/schema/p"
xmlns:tx="http://www.springframework.org/schema/tx" xmlns:util="http://www.springframework.org/schema/util"
xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd
http://www.springframework.org/schema/context http://www.springframework.org/schema/context/spring-context-3.2.xsd
http://www.springframework.org/schema/mvc http://www.springframework.org/schema/mvc/spring-mvc-3.2.xsd
http://www.springframework.org/schema/tx http://www.springframework.org/schema/tx/spring-tx-3.2.xsd
http://www.springframework.org/schema/util http://www.springframework.org/schema/util/spring-util-3.2.xsd">
<tx:annotation-driven /> <!-- error here-->
</beans>
I have explicitly included spring-aop-3.2.4.Final in my pom.xml
<?xml version="1.0"?>
<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/maven-v4_0_0.xsd">
<modelVersion>4.0.0</modelVersion>
<groupId>com.sbeko</groupId>
<artifactId>horse-accounts</artifactId>
<packaging>war</packaging>
<name>horse-accounts Portlet</name>
<version>0.0.1-SNAPSHOT</version>
<build>
<plugins>...
<plugin>
<artifactId>maven-compiler-plugin</artifactId>
<version>2.5</version>
<configuration>
<encoding>UTF-8</encoding>
<source>1.6</source> <!-- 1.7 tried here as well -->
<target>1.6</target>
</configuration>
</plugin>
<plugin>
<!-- bunch of stuff taken out for clarity..-->
</plugin>
</plugins>
</build>
<dependencies>
<dependency>
<!-- bunch of stuff taken out for clarity..-->
</dependency>
<dependency>
<groupId>org.springframework</groupId>
<artifactId>spring-webmvc-portlet</artifactId>
<version>${spring.version}</version>
</dependency>
<dependency>
<groupId>org.aspectj</groupId>
<artifactId>aspectjrt</artifactId>
<version>1.6.8</version>
</dependency>
<dependency>
<groupId>org.springframework</groupId>
<artifactId>spring-orm</artifactId>
<version>${spring.version}</version>
</dependency>
<dependency>
<groupId>org.springframework</groupId>
<artifactId>spring-test</artifactId>
<version>${spring.version}</version>
<scope>test</scope>
</dependency>
<dependency>
<groupId>javax.servlet</groupId>
<artifactId>servlet-api</artifactId>
<version>2.4</version>
<scope>provided</scope>
</dependency>
<dependency>
<groupId>javassist</groupId>
<artifactId>javassist</artifactId>
<version>3.9.0.GA</version>
</dependency>
<dependency>
<groupId>mysql</groupId>
<artifactId>mysql-connector-java</artifactId>
<version>5.1.25</version>
<scope>provided</scope>
</dependency>
<dependency>
<groupId>commons-dbcp</groupId>
<artifactId>commons-dbcp</artifactId>
<version>1.2.2</version>
</dependency>
<dependency>
<groupId>javax.validation</groupId>
<artifactId>validation-api</artifactId>
<version>1.1.0.Final</version>
</dependency>
<dependency>
<groupId>org.hibernate</groupId>
<artifactId>hibernate-validator</artifactId>
<version>5.0.1.Final</version>
</dependency>
<dependency>
<groupId>cglib</groupId>
<artifactId>cglib</artifactId>
<version>3.0</version>
</dependency>
<dependency>
<groupId>org.springframework</groupId>
<artifactId>spring-aspects</artifactId>
<version>${spring.version}</version>
</dependency>
<dependency>
<groupId>javax.portlet</groupId>
<artifactId>portlet-api</artifactId>
<version>2.0</version>
<scope>provided</scope>
</dependency>
<dependency>
<groupId>com.thoughtworks.xstream</groupId>
<artifactId>xstream</artifactId>
<version>1.4.4</version>
</dependency>
<dependency>
<groupId>joda-time</groupId>
<artifactId>joda-time</artifactId>
<version>1.6.2</version>
</dependency>
<dependency>
<groupId>org.hibernate</groupId>
<artifactId>hibernate-envers</artifactId>
<version>${hibernate.version}</version>
</dependency>
<dependency>
<groupId>org.hibernate</groupId>
<artifactId>hibernate-entitymanager</artifactId>
<version>${hibernate.version}</version>
</dependency>
<dependency>
<groupId>org.springframework</groupId>
<artifactId>spring-context</artifactId>
<version>3.2.3.RELEASE</version>
</dependency>
<dependency>
<groupId>org.springframework</groupId>
<artifactId>spring-aop</artifactId>
<version>${spring.version}</version>
</dependency>
</dependencies>
<properties>
<spring.version>3.2.4.RELEASE</spring.version>
<hibernate.version>3.5.6-Final</hibernate.version>
</properties>
</project>

Answer 1

Incomprehensible glitch with Eclipse/Java/PC. Only answer I have is: Leave the computer on overnight without touching it and it'll fix itself. Maybe, rebooting after taking the battery out would result in the same.
I can only suspect that some garbage collection happened, which cleared up a corruption in Java and/or Eclipse.