I all
I am trying to jailbreak my iphone 4 with 5.0.1(9A405)
after all the step i am getting this message and can not go beyond that point
Redsn)w.exe. has encounter a problem and need to close. we are sorry for the inconvenience. and the send report or debug ...
I ma using window Xp
thank for your help
jaky

Make sure you have Windows XP SP3 installed as I do not believe it will work at all with Pre-SP, SP1, or SP2. Secondarily, if you have multiple processors (or a processor with multiple cores), when you load redsn0w and before you click the 'jailbreak' button, open the Task Manager, find redsn0w in the list of running processes, right click on it, and change the CPU affinity to ONLY CPU 0, removing all other check marks. Then attempt to jailbreak. Last but not least, if that doesn't work, make sure you are running the program as an Administrator level user -- it will not work as a standard user.

If none of that works, it's likely something specific to your Windows XP install -- make sure you don't have any malware or spyware installed (there are boatloads of legitimate free scanners to help you fix, everyone likes their own so I'm not going to recommend one specifically), and make sure if you have any security/virus/malware/network software installed that it ignores redsn0w.exe during the jailbreak.