I've manage to defrag hard drive by continuing to use internet whilst defrag going on (if I leave it to defrag then after a while it just goes to blue screen) but I still can't get through disk cleanup without it freezing or crashing. I've managed to do everything but compress the old files on disk clean up.
Following is info from blue screen:

Technical Info
*** STOP: 0X0000008E (0XC000001D, 0XBF830097, 0XB886953C, 0X00000000)
win32k.sys - Address BF830097 base at BF8000001 Datestamp 43446a58