A Microsoft software patch which was released on Tuesday to fix four Windows flaws is seemingly giving some users a lot of trouble. The flaw in question is in the Windows component for transaction processing called the Microsoft Distributed Transaction Coordinator, or MSDTC. But installing the Microsoft supplied patch can cause serious problems, including locking users out of their PC, preventing the Windows Firewall from starting, and emptying the network connections folder.

The trouble appears to occur only when default permission settings on a Windows directory have been changed, according to Microsoft. The software maker has received "limited reports" of problems from customers but is still investigating the issue, a representative said.

Even if users experience PC trouble after installing the patch, they will still be protected against any attack exploiting the Windows flaw, a Microsoft representative said. The patch was delivered with Microsoft security bulletin MS05-051.

Microsoft says that to overcome these problems, users should restore the default permissions for the Windows folder and the COM+ catalog. The company has produced a guide to help users do just that.