MS-XP pop-up warningst

While trying to use Spybot to search my system I kept getting an XP popup warning me about a threatening virus or infection. The trick was that the site wanted me to buy a year's subscription to its service. It was a persistent pop-up, and only disappeared after I completely re-booted my system, but it's apparently out there, and I suspect that it's a worm or some such. Using Spybot and Avasti to scan my system, no infections were found, so I think this thing was a bad one. I'll have my tech try to find and delete it, but Windows XP regularly inserts updates into the system and so there are, over the period of a year, dozens of such ones, and it's hard to figure which of these, if any, was responsible for the problem.

Hello,

It is not possible for any anti-spyware-tool to detect every threat because the spyware sector is growing and developing too fast.
So it might happen that one anti-spyware-tool detects something that the other misses.
Therefore it is recommendable to run more than one security software.

But if you are infected the next time we can locate the threat in your bug report, although nothing is present after a scan. That would help to improve our database. :)

Best regards
Sandra
Team Spybot