Installing an antivirus tool will give you substantial protection against most malware - but not all. Even some of the the best antivirus engines around will fail to remove perhaps 5% of the threats they encounter. And so there's a good chance that, at some point, your system will become infected by a virus that your security software hasn't recognised.
It's a very good idea to install a second line of defence, then, and that's exactly what you get with Trend Micro HouseCall. If you think your PC might be infected (or just want to confirm that it isn't), then simply run the program, let it scan your entire system, and wait for the verdict.
HouseCall isn't a substitute for a full antivirus package, because it has no real-time protection features - it provides on-demand system scans only. This does mean the program shouldn't interfere with your existing antivirus suite, though, so it's still worth downloading as a separate line of defence. Of course HouseCall isn't guaranteed to pick up 100% of malware, either, but by scanning your PC with two antivirus engines you're much more likely to detect any threats that might be present.
Please note, we've seen occasional reports of problems where HouseCall displays an "abnormal termination" error message whenever you click "Scan". If you experience the same issue, then click Settings, choose a Custom Scan option, and point HouseCall at the drives you'd like to check. The scan should now work correctly.