Microsoft has fixed a problem that made it difficult for users of the most recent Windows Mobile devices to synch with PCs running Vista.

Tuesday night, Microsoft launched Windows Mobile Device Center 6.1, an upgraded version of the software that lets Windows Mobile users manage their phones.

The Mobile Device Center was designed for Vista users as a replacement for ActiveSync, the software that let's PC users synchronize content like calendar items and transfer content like music between their Windows Mobile phones and PCs.

However, early users of Windows Mobile 6.0 devices have complained that the Device Center doesn't synch files at all or in some cases it may lose updates to files.

"In the past, some users reported installation and compatibility issues with Windows Mobile Device Center [WMDC]," said John Starkweather, group product manager in Microsoft's mobile communications group, in an e-mail statement. "We have released an update to WMDC intended to improve the overall user experience."

Mobile Device Center 6.1 supports file synchronization for all Windows Mobile 6.0 devices including smartphones, according to Mel Sampat, a program manager for Windows Mobile who blogged about the new version.

Other new features in Device Center include synching HTML-formatted mail, allowing data connections on the phone when connected to the PC and automatic device authentication.

Microsoft also announced that in the third quarter Windows Mobile will be compatible with Office 2007. That means users of Windows Mobile 6 Professional and Standard devices as well as Mobile 5.0 touch screen phones will get a free update that will let them read and edit Office 2007 Word, Excel and PowerPoint documents.

Also in the third quarter, device makers will be able to start shipping Windows Mobile 6 devices with Office Mobile 2007 preinstalled.