Why is explorer.exe locking files?

For example, I'm just trying to rename files/delete folders, and I get the dreaded

"File cannot be deleted because it is being used"

I use unlocker to unlock it and delete, but this is becoming tedious, as it was never like this before. I am running Windows 7. I even trying starting the PC with none of the extras starting with it, and had the same issue.

 

Some options (from XP, but yours might be similar):

In Windows Explorer, switch to View-Details and then select View-Choose Details. Uncheck everything except the file name. This stops Windows XP trying to read the file - this problem affects many video, audio and graphics files.
Get a copy of free MoveOnBoot. Allows you to Move, Copy or Delete files before Windows can lock or alter them. The changes are made to your hard drive before Windows starts, hence it requires a restart of your system after you give MoveOnBoot its instructions. 3-step process:

Step 1: Locate the name of the file.

Step 2: Decide if you want to copy, move or delete it.

Step 3. Choose a destination for moving the file, or a new file name for the rename option (this option won't appear if you are deleting a file).

Click OK to confirm you want to process. Reboot ASAP, but if you are in the middle of something and want to wait, the program will run next time you start Windows.

If the file reappears (check its creation date to ensure it is being recreated), you may have spyware or a virus.