Copying to usb pendrive lasts forever

Hi,
I have 30MB of data (2x .pdf and 1x .docx) that I would like to copy to usb pendrive. Normally it lasts around 1 second. But now it lasts forever. During copying progressbar stops, but pendrive still blinks. After several minutes it is very hot, but still nothing happens. I have to take it out by force.
I have noticed that problem is completly solved when I turn off option that scans files during writing. Then everything is back to normal. So I think this is a bug.

Avast 6.0.10000, windows 7 home premium x64.

Is this problem known?

Just copied a bunch of stuff to a flash drive, no problems. Could you copy the files individually, to see if it is hanging on a single file, or file type?

Just copied bunch of mp3s and it went good.
It hangs on copying one 25MB pdf file.

I can upload somewhere this file if you want.

Ack, sorry I forgot about you :-[ ;D

Might you have any other security programs installed or recently removed on this machine?

Freshly installed 6 days windows. Only avast and windows firewall.
I can copy other files fine. Only this one is stubborn. Maye large pdfs have some problems.

Did you craft this yourself? If not, maybe try re-downloading it. Since it is this single file with a problem, makes me wonder if perhaps something is wrong with the file itself.