Saving VB Script Templates in SDL Tridion add dirty symbols

I have a really weird problem with SDL Tridion 2009 and I hope someone has already experienced this. Sometimes (not every time) when I change and then "save and close" my PageTemplates or ComponentTemplates, I then get compilation errors due to the automatic addition of strange symbols (I don't know when and I don't know who " who ") code. For example, one of the most common is "` ". Does anyone have any idea?

Thank you anyway