thats cuz when building a preview, windows checks the ENTIRE avi file
and if theres an error it hangs
ur gonna have to disable media previews
check the following list , might be helpful for other things as well
Code:
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
Credit:
http://www.tweakxp.com/tweak2123.aspx