REDMOND, WA — Microsoft Corp. is having an inordinate amount of trouble keeping the lid on its plans for Windows 7, the successor to the notoriously unpopular Windows Vista operating system.On Saturday, Microsoft “accidentally” revealed plans to make available a release candidate on May 5th. The revelatory post to the company’s partner program website quickly was removed, but not before Neowin snagged a screen capture and preserved Microsoft’s misstep.

According to the original message, the release candidate (or RC) already is available for some early adopters.

“Partners: If you have a subscription to MSDN or TechNet, you can download Windows 7 RC now,” the now-amended post said. “Otherwise, you can download Windows 7 RC starting May 5, 2009.”

The gaffe represented the second time in a month someone at Microsoft leaked “unapproved” information about Win7 RC. In March, a brief notice at the partner website advised the code would be available in May and its product key would be unlimited, but everything would be set to expire June 10th.

Also revealed at that time were Win7 RC’s product specs, which include a PC running a minimum 1 GHz 32-bit or 64-bit processor or higher, 1GB of system memory and support for DirectX 9 graphics with 128MB memory.