The company's FolderShare application is intended to allow customers to synchronize files across multiple machines, but a bug has ended up deleting them.

According to a statement from Microsoft sent to users of the service, an issue with FolderShare deleted files that contained special characters, such as trademark signs, accents and tildas, and the like.

Microsoft said it had fixed the issue, however it wanted to alert users to the problem to prevent any lost data. In some cases, the folder containing the files may have been deleted as well, and the company said affected users would have to recreate that folder.

"We sincerely apologize for any inconvenience this problem has caused," Microsoft said in the letter. "We have corrected the source of the problem and have taken steps to help prevent this from happening again."

While a small bug most likely affecting more users outside of the US market due to its nature, the problem is nonetheless an embarrassing one for the Redmond company. Still a nascent and very competitive market, blunders such as this could cripple a service's growth.

"Losing user trust from hiccups like this will only help [Microsoft's competitors to gain] market share," Michael Arrington wrote for TechCrunch. "Perhaps, like FolderShare, Microsoft will eventually buy one or more of them, too."