scan problem during copy a big folder in windows vista(U).

when i copy a very big folder from my mobile hard disk to my compouter (about 2G, morethan 2000files). the compouter will stop responses. after i disable avast 4.7 home edition, it has no problems.

Remove the protection on copied files.
Left click the ‘a’ blue icon, click Details button (if needed), at left choose the Standard Shield provider, click Customize button, then go to Scanner (Advanced) tab of settings.
Hope it helps.