Hard Drive Maxes out overnight???

Running WIN XP Pro - Dell Latitude D800 - One day I receive message that I need to create some space on the hard drive. I right click on local disk C: and it says that I only have 3.45 GB free space on a 55.8 GB drive. This laptop is about 5 years old, but I paid Dell about $5,000 to be sure it had the most memory possible at the time. It has always shown that I had over 1/2 usable space available. Any ideas as to what could have ate up all the memory overnight. Is there a new virus out there causing this? How can I check what is using all this space - I have not installed any new software - I did perform a back up to an external hard drive using Acronis - could this have backed up on the laptop instead of the external and how do I check that? HELP!

 

To check for Acronis files, use the windows search to search the hard drive (C for *.tib

To check what has used your space, download and install this program: http://windirstat.info/

 

Gosh, you are a GOD, this program showed I had some freakish .tmp file taking up over 37 GB. I deleted it and everything seems to be back to normal. Can't thank you enough for helping me out - WinDirStat pointed right to the problem.

 

Thanks for the DL collins1 smart bit of kit