Yes, there are numerous viruses that could in fact increase or decrease the hard drive storage. Some viruses add data to files, while others destroy.
I recommend you get a current virus scanner, then look for special virus software for your OS or applications.
For more information on this topic, visit these other SearchSecurity.com resources:
Virus Prevention Tip: Cleaning out a virus infection
Tech Tip: Scan and clean viruses via the Web
Best Web Links: Malware
This was first published in February 2002