Not long ago, I took a computer that was passed onto us, reformatted it, installed a fresh copy of Windows XP, and passed a shiny "new to her" computer onto Cathy. It was faster than her old computer and should have been completely problem free. It was for awhile but it’s developed an odd behavior. Every now and then, the operating system will appear to hang. For instance, this morning her menubar was visible, and I could move the mouse, but clicking on anything did nothing. I could not bring an application to focus. I had Computer Management open to the event log and left clicking on one of the event viewer items, instead of opening the item, showed the context menu (normally seen by right clicking). But unlike right clicking, once the context menu was open, clicking an item in the context menu such as "open log file…" simply closed the log file. The machine has been thoroughly scrubbed of malware, spyware and viruses. All software is updated with the exception of not yet installing Internet Explorer 8. The way I regained control of the machine was to close an open Skype chat window.
The slow downs seem to correspond to this error in the event viewer (\Device\Harddisk1\D refers to the Seagate external USB Freeagent drive):
An error was detected on device \Device\Harddisk1\D during a paging operation.
This is bizarre.