Windows Explorer slow response when disconnect from the network
I found this knowledge base article which supplied a hotfix that corrected the issue. I also found out this fix is included in Windows XP SP3.
This did not solve all cases. I also found out this issue is also often caused by the WIA server. Stopping and disabling it will fix it.
I experience this a lot as well. It has to do with indexing network directories. If you have a network with hundreds of GB of storage, you will see this often. In XP, it's a bug, and I know Vista and 7 work much better with indexing files. I usually kill the dialog box and open it again. Slow, but it almost always works to get the access I need. I don't find the need to actually disconnect the drives as you say. One other thing that I found helps is always having these directories open for faster access and the ability to transfer files independent of apps that need to save/open. Good luck.
I had this problem when one of the document icons or shell extensions was registered on a network drive. Check in the registry under HKEY_CLASSES_ROOT if some of registered DLL files are on a mapped drive or on
Also check the solution from this question.