Removing media preview worked for me:
http://www.tweakxp.com/tweak2123.aspx
If you have a large movie clip and it either is corrupt (ie. no index from a
partial download) or it uses an unsupported codec, then Explorer tries to
load the whole file. This can slow your computer a lot and prevent
deleting/renaming/moving/etc the file until it's finished.
Simply do the following steps:
1) Open a command window (Start->Run, type in 'cmd' hit enter)
2) To remove image preview, type and hit enter
regsvr32 /u shimgvw.dll
3) To readd image preview, type and hit enter
regsvr32 shimgvw.dll
4) To remove media preview, type and hit enter
regsvr32 /u shmedia.dll
5) To readd media preview, type and hit enter
regsvr32 shmedia.dll
Simple.