Consumers are being that advised that using multiple antivirus and antispyware software can lead to compatability problems.

Kaspersky Labs said people should be aware that if run at the same time it could cause a PC to crash.

Many consumers use a combination of both free and paid for security software, such as downloading the free anti spyware program Ad-Aware with a paid for antivirus product.

Recently security company McAfee  admitted that there was a problem with using its antivirus software while competing products were also installed.

Brian Trombley, Product Manager McAfee said that the problem led to a warning if Ad-Aware was detected. He said that the problem has now been fixed and the message will no longer appear.

David Emm from Kaspersky labs explained that it is not a good idea to use multiple antivirus and antispyware programs because they use a technique called real time scanning.

This scans files as they are opened rather than waiting for a full system scan. This works at a very basic level in Windows and may cause problems if two programs attempt this at the same time.

He said the company hadn't been alerted to any reports of specific problems from its users. But because Kaspersky was aware of the issue, users of its software will be requested on installation to removal other anti spyware software such as Spybot Search and Destroy, which also uses a real time scanner.