stop: c0000221 unknown hard error on blue screen

I have a Thinkpad R51 laptop running with Windows XP service Pack 3 bought about a year ago and never had any problem. Yesterday suddenly while working on the same I received a Blue Screen with the error mentioned in the subject line above followed by “SystemRoot/System32/ntdll.dll.” Just before occurring this BSOD, I also saw a message about "Dumping physical memory". Well according to this message I guess it is something related to corrupted ntdll file, right?

Anyways, since then my laptop is not booting any more. It hard reaches sometimes to Boot Menu option and restarts again with Blue Screen. Hence I’m not able to select Safe Mode as well. Hope you guys can provide me some help.

Thank you.

I’m not sure it is related to ntdll.dll file but as far as I know it is the result of faulty Hard Drive or is the notification of hard drive going to be faulty soon. The only option you have to insert Windows CD and try re-installing Windows. See if your hard drive allows you to do the same.

Thank you very much for the help Toby-Martin. Meanwhile i found the documents i received while purchasing this laptop and saw that it is still under warranty. Hence i took it to Service Center, they said that the problem is with just Windows Corruption and they will fix it after taking the backup. However i will consider your suggestion as well and will soon replace the hard drive. Thanks again.