hi there and thanyou for a quick and helpful respond
can not boot into safe mode at all.
pressing f8 get screen with all options selecting safe mode and then pc restarts normally.
tried run>msconfig>boot.ini>tick safe mode and then struck disaster
computer startted and then beause it couldnt boot in safe mode was constantly restarting.i couldnt go to last working configuration or anything so i had to reinstall the xp pro again
(well i suppose that is "best:way to learn your pc)
my xp pro is updated with service pack 2 and all patches from microsoft are up to date.
i did sfc / scannow and all is ok there( dont know if that has anything to do with it)
is it any service or something which is stoping thsi or what?any suggestion are welcome