Getting Disk Space Low warning and shows full...goes away after reboot

I am getting a Low Hard Disk Space warning, this happened about a week or so ago but went away after I rebooted a few times. I have a 500GB hard disk and right now it shows about 5GB free. Normally I have about 200GB. I am going to try rebooting to see if it works again but I'd like to know what the cause is and if it is a sign that my hard drive is going bad. So far since my 1yr warranty expired about 2 months ago by battery has went bad and I've had one of my RAM cards go bad. i haven't been to happy with it lately.

Click Computer, right click the drive in question, select properties. Click the Tools tab, click check now. Report back.

I set the checkdisk to run at reboot and rebooted. It fixed several errors.

After rebooting the disk space was back to normal. I then ran some updates for my laptop touchpad and I got a blue screen. after rebooting from that the disk space was back to nearly full.

I rebooted and now it is back to normal.

Please post your BSOD Minidumps to be analysed

http://www.sevenforums.com/crashes-debugging/96879-blue-screen-death-bsod-posting-instructions.html

Here's the info.