Among other things, the February patches were suppose to fix a security flaw in Microsoft's SMB file-sharing protocol. This bug is exploited in the wild but so far there's no evidence it can be used to compromise a system:
SMB should, of course, be blocked at the firewall, so the risk of remote exploitation of the SMB flaw should be relatively low. It's currently believed to only permit crashing of affected systems, so while it's inconvenient, it should not lead to system penetration or compromise. Nonetheless, being forced to wait another month for a fix for something so publicly known is an uncomfortable position to be in.As stated above, there's no official word about why Microsoft made this unusual decision. ZD Net's Microsoft watcher Mary Jo Foley heard some speculation that there may be a sudden issue with Microsoft's build system but the company refuses to go into the details.