SEVERE: Allocate exception for servlet myServletName

Using Spring Tool Suite 3.6.3, I added the following to my POM.XML of my Maven Web project.

<dependency>
    <groupId>com.MyCompany.sei</groupId>
    <artifactId>MyCompany-archetype-war</artifactId>
    <version>1.0.2-RELEASE</version>
</dependency>

It successfully download this dependency and showed this new dependency in the Project Explorer->Libraries->Maven Dependencies folder

However, now when I try to access one of the test jsp pages in my HelloWorld web app running on the following STS web server "Tomcat v7 Server at localhost," I get the following error with nothing else changed.:

Feb 16, 2015 12:25:28 PM org.apache.catalina.core.ApplicationContext log
INFO: Marking servlet fitTrackerServlet as unavailable
Feb 16, 2015 12:25:28 PM org.apache.catalina.core.StandardWrapperValve invoke
SEVERE: Allocate exception for servlet myServletName
java.lang.ClassNotFoundException: org.springframework.web.servlet.DispatcherServlet
    at org.apache.catalina.loader.WebappClassLoader.loadClass(WebappClassLoader.java:1720)
    at org.apache.catalina.loader.WebappClassLoader.loadClass(WebappClassLoader.java:1571)
    at org.apache.catalina.core.DefaultInstanceManager.loadClass(DefaultInstanceManager.java:506)
    at org.apache.catalina.core.DefaultInstanceManager.loadClassMaybePrivileged(DefaultInstanceManager.java:488)
    at org.apache.catalina.core.DefaultInstanceManager.newInstance(DefaultInstanceManager.java:115)
    at org.apache.catalina.core.StandardWrapper.loadServlet(StandardWrapper.java:1148)
    at org.apache.catalina.core.StandardWrapper.allocate(StandardWrapper.java:864)
    at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:134)
    at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:122)
    at org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:504)
    at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:170)
    at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:103)
    at org.apache.catalina.valves.AccessLogValve.invoke(AccessLogValve.java:950)
    at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:116)
    at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:421)
    at org.apache.coyote.http11.AbstractHttp11Processor.process(AbstractHttp11Processor.java:1074)
    at org.apache.coyote.AbstractProtocol$AbstractConnectionHandler.process(AbstractProtocol.java:611)
    at org.apache.tomcat.util.net.JIoEndpoint$SocketProcessor.run(JIoEndpoint.java:314)
    at java.util.concurrent.ThreadPoolExecutor.runWorker(Unknown Source)
    at java.util.concurrent.ThreadPoolExecutor$Worker.run(Unknown Source)
    at org.apache.tomcat.util.threads.TaskThread$WrappingRunnable.run(TaskThread.java:61)
    at java.lang.Thread.run(Unknown Source)

So I comment out the added dependency and try again and get the same error again.

Looking at the differences with the last working version that I checked into SVN, I see that the following files have changed:

.classpath
.project

When I compare the new versions to the old, they look identical, with the exception of having some shuffling of the buildCommand and classpathentry nodes.

I as green as the summer grass when it comes to Java development. I at a basic level know that the info in these files is used to list dependencies and where to find jar files but I am puzzled why the web site now returns an error when reverting back to the original code. I've seen some references to running "Maven->Update Project" but this doesn't work. I've also tried to revert to the old versions of the classpath and project file and still it does not work.

I'm sure that something is getting out of whack here. I even tried Sopring Tools-> Reset IInternal Cache on the project with no luck.