Microsoft's latest security patch is causing issues for users of several HP products including cameras, scanners and printers.

Problems include blocked access to special folders like My Documents and My Pictures, and Office applications that stop responding when users try to save files in the My Documents folder.

Microsoft said in a security bulletin that the issue could also cause Internet Explorer to become unresponsive. 

Another problem affects users of the Sunbelt Kerio Personal Firewall who are receiving prompts from the application when Internet Explorer is trying to launch a security application included in the update. 

Microsoft released an application as part of last week's security patch that validates shell extensions before they are initiated by Windows or Internet Explorer.

This prevents attackers from installing code on a system when a user visits a specially crafted website.

But the Sunbelt Kerio Personal Firewall will prevent Internet Explorer from executing the new application as a security measure.

The HP issues are caused by the vendor's Share-to-Web software that comes bundled with several of its hardware products. The application is automatically started when a system boots up, and is flagged by the new shell validation tool.

"The change is not related to a software vulnerability, merely a product behaviour change to make the product more resilient to attack," Microsoft security programme manager Mike Reavey said in a blog posting. 

Microsoft has provided instructions on how to repair both issues on its website.