I have ShopSavvy and Barcode Scanner, both work well. They are not far down in the 'all applications' section of the market if you sort by popularity. Or just search barcode scanner
I'm having the same problem
It started happening just after I uninstalled Advanced Task Manager.
Edit/Update: I also did an update for my anitvirus around the same time. I uninstalled the antivirus program, and now it is working fine.