XP Not Automatically assigning drive letter to USB flash drives

I had a problem, maybe a virus, and I had to repair my XP Home Edition on my HP laptop. Then I downloaded all the Windows updates from Microsoft. Everything appears to be Ok, except when I plug any flash drive type of device (drive, camera, cellphone) into my USB port. For example, when I plugged in my flash drive, windows recognized it and installed it. Device manager shows it in the USB devices and lists it as a disk drive. The only way I can access it is to go to Computer Management, Disk Management. The drive shows up with no letter. I can select a letter and then access it by through Open on Disk Management (it does not show up in "My Computer.") When I transfer any files to it, I am told that it only supports short names (8 letters.) When I remove the flash disk and plug it in again, I have to go through the same process. If I have not shut down in between, it wants a different drive letter. I know the USB is ok as when I plug in my remote hard drive it recognizes is normally.