Microsoft plans to release five patches--at least one fix rated Critical--on Tuesday, a week after the software giant rushed out an emergency update to fix a vulnerability in how the Windows operating system handles animated-cursor (.ANI) files.

The company announced its plans on Thursday, as part of its regularly scheduled monthly patch process. The software giant typically announces the number and maximum severity of updates the week before the company's regular patch day, the second Tuesday of the month.

In April, the company plans to release four updates to close security issues in its Windows operating system, and another patch to close unspecified vulnerabilities its Content Manager Server software.

Microsoft announced the forthcoming fixes two days after it rushed out a release to patch seven security issues in the Graphics Device Interface (GDI), including a critical flaw in how the Windows software handled animated-cursor (.ANI) files. A criminal group responsible for using compromised Web sites to spread malicious software had already started using the ANI flaw to install their code from at least three servers in China, security experts said.

Of the seven issues patched on Tuesday, only three affected Microsoft's latest operating system, Windows Vista, and only the ANI flaw was rated Critical by the company.