Ok, here's the best thing to do in my opinion.
First, enter your Task Manager processes screen. On Win 2000, I use CTRL-ALT-DEL , Task Manager, then select processes.
If it is a program running on your computer, it will likely be found in here.
I would then go down the list one by one and perform a search on them all initially. So for YPager.exe, I'd do a search on Google for "YPager.exe virus" and browse the articles. This will not only give you better insite into where the virus is hiding, but will inform you about what exactly your system is running.
Also, If you have run Spyware, adaware, etc.. and have not been able to remove it, but can see the name of the file on your desktop, also try doing a search on that. On Google, as well as your hard drive. I have found multiple dialers over the years that have installed themselves this way.
Hope that helps