This doesn't sound to good ....Maybe you should run an AV and Spyware scan to start with and then post a Highjack this log at one of these sites...
http://www.bleepingcomputer.com/ http://www.spywarewarrior.com/index.php
I have had the shared folder giving me the error message, but never LW and if you cannot run a defrag and your IE crashes, there has to be something a bit more complicated involved...
The sites I have recommended are mannned by experts, so give them ago...
Please let us know how you get on....
