Redmond asks for trial to be postponed; meanwhile email disclosures causing embarrassment.
Microsoft has appealed against the decision to afford class action status to the Vista Capable lawsuit.
The company has asked for the trial to be temporarily halted to prevent the further disclosure of emails that have proved highly embarrassing.
Microsoft said in its petition that the court had made "errors" in allowing the case to be opened up to class action status as it exposed the company to potentially huge numbers of complaints that had little relevance.
"Microsoft produced nearly 50,000 pages of documents in the course of class discovery at a substantial cost," the company said.
"The sheer size of Microsoft makes this process an enormous and costly undertaking.
"Without a stay, Microsoft fully expects to spend substantial additional sums in out-of-pocket discovery expense, not to mention the lost productivity of employees whose testimony will be required."
Many of these documents have proved embarrassing for Microsoft as they show senior management expressing grave concerns about Vista and the Vista Capable campaign.
Mike Nash, corporate vice president for Windows product management, wrote in an email: "I personally got burnt. Are we seeing this from a lot of customers? I now have a [US]$2,100 email machine."
Jim Allchin, then co-president of Microsoft's Platforms and Services Division, wrote in another email: "We really botched this. You guys have to do a better job with our customers."