I agree with Chuck, you probably have a virus.  Norton and McAfee appear to
have both missed the latest viral attack method, virus's hidden in zip
files.  I know Panda Anti-Virus (www.pandasoftware.com) has been catching
these virus's.  Having no experience with TrendMicro, I don't know if
TrendMicro will catch these as well.

After you run a good virus scanner (not Norton or McAfee), run a chkdsk /r
(Win 2000/XP), chkdsk /F (NT4), or ScanDisk (Win95/98/ME) on your problem
system to clean up the drive's structure.

Mike Ober.

(My antipathy towards Norton is based on experience with Norton bogging down
systems.  My antipathy towards McAfee is a result of having to spend a week
cleaning up our corporate network after a virus infected it when _ALL_ the
workstations and servers were up to date on McAfee's AV sig files and AV
engine.  Panda started catching Sobig/B the day it came out, updates their
sig files daily instead of weekly, and I haven't had a virus hit in three
years.)