TomTom has issued a fix for a fault that had caused some of its satellite navigation devices to malfunction.
The firm said that a problem with its global positioning system firmware - code embedded into the devices - had caused models worldwide to fail to identify their location.
Affected users were presented with a grey screen and a message saying the machine lacked a GPS signal.
The firm said a software update was now available to correct the problem.
The Dutch company said that the issue first emerged on 31 March.
It said the several models were affected including both new and discontinued products. It suggested that owners of the following devicesshould install the new code:
- Start 20/25
- Via 110/120/125
- Via Live 120/125
- Go Live 820/825
- Go Live 1000/1005/1005 World
The process involves connecting the sat-nav device to a PC and then downloading the software. Users who had not previously created a TomTom account will need to sign up to the service.
Messages posted to the firm's user forums suggest the update works for some owners, but others have complained they are still facing problems.
"The software update downloaded and got stuck on 99% downloaded. It didn't install properly and now my PC can't even connect to it," wrote one user.
Another added: "There seem to be some devices where the fix is is not working properly. I guess we have to wait for TomTom to give us more information about this."
A spokeswoman for TomTom told the BBC that the firm believed some users had not followed all the installation instructions. She said the company was certain that its solution should work on all affected devices.
She suggested that users still experiencing problems should contact TomTom for further help through its website's support pages.
She said she could not provide a figure for the number of users affected.
A thread entitled "No GPS Signal"on TomTom's site had attracted more than 700 posts by Wednesday morning.