Gmail users, including those who use it for work as part of the Google Apps hosted suite, experienced problems accessing the service last week.

Reports started streaming into the official Gmail and Google Apps discussion forums on Thursday and continued Friday morning.

It's the third time in the past two weeks that Gmail users have been locked out of their accounts due to the "502 Server Error" login problem.

In the middle of last week, an undetermined number of individual and Apps Gmail users were hit, and it took Google about 15 hours to restore the service for them.

Then on Monday of this week the problem resurfaced. A broad group of Gmail users, including organizations that use it as part of the fee-based Premier version of Google Apps, were affected.

Now the problem is back, according to multiple reports from users. It's not clear how many people have been affected by this latest problem, but those who are detailing their troubles in the discussion forums describe the outages as prolonged.

"Still down. 24 hours and counting. This ceased to be funny long ago. Any of the other users here have any recommendations for another e-mail provider? It's time to start voting with our feet and leaving for greener pastures," wrote a user identified as Howardf42 on Friday morning in a thread devoted to the 502 problem in the Google Apps discussion forum.

Google spokesman Andrew Kovacs said via e-mail that "a small number" of Gmail users and "some" Apps users were impacted by the problem, which is still outstanding and being worked on as of 5:30 p.m. U.S. Eastern Time on Friday.

"We know how important Gmail is to our users, so we take issues like this very seriously, and we apologize for the inconvenience. We encourage anyone having technical difficulty to visit the Gmail or Google Apps discussion groups where we're posting status updates," Kovacs wrote.

Google is a major proponent of the idea of delivering applications and computing services via the Internet, popularly known as "cloud computing."

However, when vendors experience technical problems in their data centers and the performance and availability of the applications is affected, IT and business managers feel helpless, because they can do little to restore the services, while their end-users clamor for solutions.