my xp sp1 512 mg ram system freezes frecuently, when i go to the task manager the CPU is 100 percent used by one process "explorer.exe", then i finish the process, then new task, explorer.exe, but in a few minutes the problem is again. This problem just occurred out of no where after a reboot. Whenever I am using some files or programs, Windows freezes. This is because some program or malware replaces original explorer.exe or his dll links. i know there are programs that can backup the explorer and the links at the original status. The system was scaned for virus or malware and nothing. Anybody can help, What could I do???