Mmm ... you're right to be reluctant to use that. I'd be. What I'd do is, as the above post said, wipe it off with a clean cloth. If it's not thermal grease at all but those melt-and-stick thermal tape-like blobs, then you may have to work at it a bit ... but I wouldn't use lacquer thinner at all. Also, make sure to wait until your CPU is cool and unplug the computer from the wall ... nothing worse than putting ice-cold water on a hot CPU .. or one that's attached to a plugged in PC.

Hopefully this'll help somewhat. Your only obstacle will be if it is the sticky thermal tape stuff, and that usually takes a bit of work with a fingernail, and that's it.

~N~