Boot Error: Ntldl.dll Missing or corrupted

[Underhanded]

When I boot up Windows XP home on my laptop it says the system file ntldl.dll is missing or corrupted. This laptop had been working perfectly yesterday. Everything was running great, no apparent spyware viruses or anything of the sort. I hadn't installed anything in awhile, and then suddenly, this afternoon, when I booted it up the blue screen came up saying I was missing this file. I have had this EXACT same problem 3 times in the last 4 weeks with this laptop.
I don't understand what could be going on... I assumed it was a program that I installed that messed it up, but I hadn't installed anything this time... I know I didn't give a lot of information, if you want more feel free to ask. I already tried all I could to fix it (ran ERD commander and tried to fix it, repaired the OS, did lots fo checks.. everything I ran said everything was working just fine. but it still wouldn't boot. I finally had to reformat it.. for the 3rd freaking time.. Anyone have any ideas as to why it would be doing this? Seemingly deleting a system file of its own will? GAH... it's probably something really obvious thats my fault...
Well! if it is! Do tell.
Anyways, thank you for your time anyone who replies.

[Statica]

Welcome to PCMech.
Is the error ntldl.dll missing or is it ntldr missing? ntldl.dll is not a Windows file, it's like a malware and you need to scan your PC with at least a few options to make sure that it's clean. http://housecall.antivirus.com/ is one way to scan.

ntldr missing is a more serious issue and there are a number of possible reasons for it http://www.computerhope.com/issues/ch000465.htm deals with some of them.

[Underhanded]

My mistake. It was indeed ntldr.dll that was missing. Thank you for the link, and also thank you for the welcome =D I apologize for misstyping the name of the dll file ^^; In any case, I got it working again... Thank you for the help.