This month's Patch Tuesday has become a problem with some (no real surprise there), with one of the 12 updates that MS issued causing problems with dial-up networking and some scripts. The MS06-025 patch, which patched the Routing and Remote Access service, caused changed which apparently render many types of dial-up connections worthless. If you are using dialup, Symantec suggest a standard security practice of filtering vulnerable ports, including the RPC ports, until an updated patch is released.
The conglomerate Microsoft patches often do have issues with them at first, which is why it's good advice for all IT Administrators to roll out patches at-will after examination.