I can confirm that myself & three of my colleagues have also been seeing this issue while using STS 2.3.1 & 2.3.2 over the last few months.
To date we cannot find a specific pattern as to when the errors will appear / how to correctly resolve the issue (although we will try the workaround suggested by bcoffe)... sometimes a simple project clean / STS restart seems to fix the issue, other times doing bizzare things like installing & uninstalling plugins seems to resolve the issue but none of these work consistently.
It can quite often happen once we've done a fresh install of STS, created a new workspace, and then re-imported all of our existing projects.
In addition it sometimes requires a "fake edit" of the bean configuration files (select all, cut, save, paste, save) before the errors will disappear.
If you need any more info just give me a shout.