SP4 for W2K was released today 6/26/03. First reports are looking cautious,
DO NOT INSTALL IT WITHOUT RUNNING A BACKUP.

STEP 1: turn off all antivirus software before installing SP4.

Ok, before reading about the problems, I should mention that I have applied SP4 to all my machines
now and have not had a single issue with it on any of them. That includes webservers and desktops so
don't pass this fix up because you hear about problems, there are always problems with updates.

(1) Some folks are reporting incomplete installation, more as it develops. It's somehow related to
additional software they have installed or running. All have been able to gracefully back out of
the installation.

Seen mention of issues that may be related to URLscan and certain mime types being blocked
that could prevent certain parts of the SP from being installed, just rumors at this point, nothing confirmed.
The errors are a "unable to write scriptmaps metabase entry" and a "regsvr32 failed to register 5" error.

(2) I've been told if you have automatic updates disabled, SP4 will re-enable them so
you need to check that after applying the service pack. (this is confirmed working as designed, see section 3 of the EULA for a shock)

(3) Two reports of icons changing, AD users & computers icons and all MS Office icons changed to the
unknown type icon. Seems to only happen on servers.

(4) If you remove Service Pack 4 (SP4) from a Windows 2000-based computer, 
your scheduled tasks will NOT run. Solution and full explanation can be found here. Removal is far from complete,
restore from backup is the only good way to remove it.

(5) Some issues with VPOP3 and RAS not functioning correctly after applying SP4.There is now a fix for the VPOP3 problem. Apparently SP4 complained when the buffer passed for results was larger than expected, so you can't use a generic buffer now, it has to be correctly set up. (note just received confirmation on a second VPOP3 problem, been told that VPOP3 doesn't recognize RAS intermittently after applying SP4)

(6) A few reports of 100% cpu usage after applying the service pack, one solution was to let it sit overnight and by morning the cpu had returned to normal, speculation was it was some sort of dll cleanup operation going on.

(7) 2 reports now of SP4 and one of the post SP4 hotfixes messing up Dell poweredge servers. No specifics yet as to the cause. I had this happen on a Dell poweredge 2450 server but the problem was that it wouldn't shutdown properly after
applying the service pack, reloading the dell intelpro100 driver cured that.

(8) RightFax Enterprise Server ver 7.2, 8.0, & 8.5 has an issue with SP4, seems once you install SP4 you can't login to the admin interface (it works otherwise). It generates an error "Login to fax server <servername> is not currently possible because the Rightfax RPC Server Module and/or the RIghtFax Database Module are not currently running." even though the service is running. Uninstalling SP4 resolves the issue so at least it's reversable for now. Vendor is aware of the issue.
NEWS: there are rumors of a fix available, file called EFM.EXE from Captaris (still beta afaik)

(9) SQL server 2000, had one report that the user tried to install SP4 and received an error message "can't connect to the metabase" and then it gave him the choice to continue with an incomplete upgrade or to back out so he choose to back out. I've found one other user who also had this problem. One of the users had stopped the IIS service (which was installed on his machine) but that didn't seem to make any difference.

(10) http://www.theinquirer.net/?article=10499  The note says that if you have installed Service Pack 4 for Windows 2000,
you might well find that Autodesk VIZ 4, 3D Studio VIZ 3 and 3D Studio VIZ3i won't open any .max files any more.

(11) A new image of w2k+SP4+ latest w2k Intel Pro 1000 MT results in a BSOD with RIS. Same drivers etc work fine with slipstream SP3 image. Driver works fine with SP4 just cant get it in via RIS.

(12) New one, seems SP4 plus hotfixes have done something to my system that affects atguard and crazybrowser. Crazybrowser doesn't completely load pages anymore for some reason. Definitely related to the fixes but still trying to track down the issue.
FIXED!!! ok here is the cure for atguard. 

(13) After installing SP4 on a Dell poweredge 4400 the user found active directory was completely corrupt. Dell said it was an incompatibility with either the raid controller or the array manager software and advised the user never to install a SP on a dell system unless provided by dell. Seems kinda like a reason not to buy dells if you ask me..

(14) Reports of problems installing office2k on slipsteamed sp4 pro installs. system file errors.. "insert sp4 cd"

(15) After installing SP4 the following error appears in the eventvwr. It seems
to be fixed by reinstalling .NET Framework. Error: "WMI ADAP was unable to process the .NET CLR  Networking performance library since one of the data blobs reported to have classes but had zero size."

(16) Seems SP4 breaks the AS/400 iSeries Operations Console. It gets an app error after install of SP4. Uninstalling the SP allows it to work again.

Also, these KB articles are handy:

Email me your results and I'll post as they come in.

This is another site dedicated to listing problems and solutions for SP4