A software bug is leaving VMware customers unable to log in to virtualised servers.
The issue began early on Tuesday when users attempted to power up virtual systems running the company's ESX 3.5 software. The user is greeted with an error message indicating that the machine's 'power on' function failed due to an expired licence.
The company said the issue is due to a timeout mechanism that had been left on and set to expire on August 12. This, said the company, caused the system to lock out users and believe that the licence had expired.
The issue only affects systems that run ESX 3.5 Update 2 and ESXi 3.5 Update 2.
The timeout feature is often used by developers when distributing test builds to users in order to prevent them running and distributing test versions of the software indefinitely.
In a blog posting, VMware assured users that the issue was not a security risk and that the cause of the problem had been found.
"Several customers have been worried that their ESX systems had been compromised by an attack and that this was the cause for not booting," the company said.
"The problem that surfaced today is not related to exploitation of a security issue on ESX."
The company said it is in the process of producing a temporary "express patch" due to be released by 6pm on Tuesday evening US pacific time. Users can also temporarily work around the flaw by setting the system's date and time to an earlier day.
VMware hopes to have a permanent patch ready for release by noon pacific time (20:00 GMT) on Wednesday.
IBM and Technical University of Munich team demonstrate how Shor's algorithm, which can't be cracked by conventional computers, can be solved quickly with quantum computing
Hubble Space Telescope finds superflares from young red dwarfs could strip away planetary atmosphere
Younger stars are 100 to 1,000 times more energetic than when they're older
Two of the big four supermarkets will use the system to control sales of restricted products
PUBG news and updates: November's Update #23 to bring new Skorpion pistol and changes to blue zone visibility
Genuinely useful side-arm coming to PUBG in Update #23