I just fixed a problem I've been having for the last two weeks with Windows 2000 - my system would pause and stop responding for 15 - 30 seconds whenever I:

* clicked the Start button
* right-clicked on a file or folder
* accessed the Look In / Save In drop down boxes when opening/saving a file

Annoying! It was difficult to figure out what was happening. I was up-to-date on all SPs, but I had recently installed a bunch of software. Turns out Win2K was the culprit.

It seems that Windows Explorer attempts to validate all network connections when performing any of the above tasks. A drive was mapped on my machine to a non-existant server, which caused the delayed response. Once I deleted the mapped drive, the system began to respond normally. Hope that helps somebody!