Microsoft messed up Update Rollup 1, that caused compatability problems with several vendor applications such as Citrix, Sophos, and some parts of Microsoft Office. Programs were unable to access floppy disks, or even crashed more often, or simply didn't work. Microsoft earlier remarked that only a handful of applications failed after Update Rollout 1 was installed, but was later forced to acknowledge more incompatabilities
Microsoft has patched the Update Rollout 1, now at version 2, and has posted the repair on their websites.
Microsoft has removed Windows 2000 from active mainstream support on June 30.