Main Drive C is filling up for no reason

[monostory]

 I have windows XP professional.   Hewlett Packard.  I gig hard drive.  I have about 15 ten page business docs on it, plus about 20 photos. Each time I try to free up disk space then defragment  my main drive space is reduced.  I now have 23% of free space left.  I would appreciate it if someone could tell me what is filling up my computer.  I disk cleanup and delete browsing history.
M

[Dusty]

A few details would be of benefit.  Please read this and include your hdd specs and what you've tried to do to reduce usage.

[Allan]

The usual suspects are: System Restore, Temporary Internet Files, Recycle Bin, Malware

To rule out the last, do a FULL SCAN with BOTH your anti virus utility and either (or both) MalwareBytes or Super Antispyware

[monostory]

Hey.  I followed the advice  re antivirus and malwarebytes.  As soon as I downloaded Malware my computer went berzerk.  The screen seized.  For some reason Roxia media kept coming up.  I ended up restarting and deleting Malware. What could this be? 

[Allan]

When you downloaded it or when you installed it? Boot to safe mode and run the scan from there.