This behavior can be caused by severe fragmentation on your hard drive.

If you're running Windows 7, it does not de-fragment your hard drive automatically like Windows 10 does.

The solution could be to run a Disk Defrag on your C drive. You can also run a Disk Check to check for any bad sectors.

A quicker workaround though would be to go to the System Settings in AGi32 and change the location of the Working Files.

Go to Tools > System Settings

From here go to the File System tab and change the Working Files directory by clicking on Browse and set it to C:\Temp.

Restart AGi32 and clean out the old file location. Files should open normally now.