UPDATE: Raluca from BitDefender has posted a comment at this link with more details on how you can fix this problem.
Today, BitDefender 2010 users received an update that brings up a fake trojan.fakealert.5 error and falsely detects safe files as viruses. This problem only occurs on those that are using 64-bit operating systems with the 64-bit version of BitDefender 2010.
Fix Trojan.fakealert.5 problem
The BitDefender company is working on fixing the trojan.fakealert.5 problem. They have made a post on their support forums mentioning that they will be issuing an automatic update as soon as they can.
If you were affected by this update, let us know in the comments. Feel free to post any solutions to fix this problem as well.