Windows – Fix ‘C:\Program Files\Microsoft’ Opening at Startup

I'm not sure this question belongs on ServerFault, so feel free to close it if it doesn't.

I'm running Windows XP.
A few weeks ago, my computer started to automatically open the C:\Program Files\Microsoft folder at startup. I thought it was a utility I had installed that caused it, so I uninstalled, but that didn't solve the problem

I searched on Google and found a similar question, and consequently I checked my scheduled tasks, and the startup menu, but didn't find anything that looked like it was opening that folder. I also took a look at the registry keys mentioned there' but I'm not an expert on registry, so nothing struck me as odd.

Has anyone run into such an issue? Or do you have any suggestions as to what else I can do?