From reading all of the other posts, then yes, I think that a re-install might fix the problem.
If you have downloaded content, then back up the local folder inside [hard drive where Trainz is]\Program files[if trainz is there(it is by default)]\Auran\TRS2006. This contains all of your custom content.
To replace this content, then copy the local folder back into the TRS2006 folder on your hard drive, after re-installing it, and then delete the assets.tdx file from the TRS2006 folder, and the assets.bku file from the TRS2006\cache folder. then open up CMP and allow it to sit and rebuild the assets database.
If this doesn't work, then I'm sorry, but it's all I can think of.
Hope this helps!