It seems a fairly steady stream of these security warnings come out of Redmond every month, and working for a security software company, the news does get old and tiring quickly. Even though it’s repeated ad nauseum, I’ll continue to post these in an effort to persuade the 28% of visitors using Windows who visit my site (based on browser data passed to my logging tools) to switch to a Mac.

Microsoft on Tuesday warned of three “critical” security flaws in its Windows operating system that could allow attackers to take control of a computer. In response, the company issued patches to fix the problems as part of its monthly security bulletin.

One of the critical vulnerabilities appears in some versions of Internet Explorer that could make it possible for an attacker to use the Web browser to take total control of a PC.

The other two “critical” vulnerabilities were in the Windows operating system itself.

The company defines a flaw as “critical” when the vulnerability could allow a damaging Internet worm to replicate without the user doing anything to the machine.

The company also issued another security warning it rated at its second-highest level of “important” for Microsoft Windows as well as one it gave a severity rating of “moderate.”

A vulnerability defined as “important” is one where an outsider could break into a machine and gain access to confidential data but not replicate itself to other computers, Microsoft said.

Microsoft has been working for more than three years to improve the security and reliability of its software as more and more malicious software targets weaknesses in Windows and other Microsoft products. So far, it looks like they’re still falling short.