Microsoft has released an update for all supported versions of Microsoft Windows.
The update revokes the trust of the following DigiNotar root certificates by putting them in the Microsoft Untrusted Certificate Store:

• DigiNotar Root CA
• DigiNotar Root CA G2
• DigiNotar PKIoverheid CA Overheid
• DigiNotar PKIoverheid CA Organisatie - G2
• DigiNotar PKIoverheid CA Overheid en Bedrijven
• DigiNotar Root CA Issued by Entrust (2 certificates)
• DigiNotar Services 1024 CA Issued by Entrust
• DigiNotar Cyber CA Issued by GTE CyberTrust (3 certificates)

The reason: Fraudulent SSL certificates are issued by DigiNotar after a breach

Download patches: http://support.microsoft.com/kb/2616676
http://technet.microsoft.com/en-us/security/advisory/2607712

http://googleonlinesecurity.blogspot.com/2011/08/update-on-attempted-man-in-middle.html