Looks like Citrix now has a fix for the SP4 rollup issue.
Citrix this week posted hotfixes for two of its products that were crashing after users installed Microsoft Update Rollup 1 for Windows 2000 Service Pack 4.
Users reported problems on the Citrix Knowledge Center and on the Shavlik patch management mailing list shortly after Microsoft released Update Rollup 1, a collection of more than 50 security fixes for the five-year-old Windows 2000 operating system.Read CTX107051 here.
[Via Thincomputing.net]