O2 has temporarily suspended the rollout of Android 2.2 to HTC Desire handsets on its network after the update caused problems for some owners.
The operator began the over-the-air delivery of Froyo on Monday, but customers quickly began reporting issues with the new mobile OS on the company's support forum.
"I think the update may have bricked my phone. It won't start up now, gets stuck on the O2 blue start-up screen," a customer by the name of 'Potzy' wrote.
That experience was echoed by other users. "I did my update this morning now the phone crashes as soon as HTC Sense starts, then again. I've tried removing the battery, no luck there," wrote fellow upgrader 'JFreeman'.
O2 responded swiftly on Monday to the reported issues by suspending the delivery of the operating system.
"We saw that a small number of customers were having problems installing the update. While we investigate these issues, we have put the 2.2 update on hold. At the moment, we don't have a new date for when the update will be available," an O2 spokesman said.
Other O2 customers reported that the Android 2.2 installation went ahead with no problems after they freed up 50MB or more of the Desire's memory.
In August, Vodafone made changes to its Android 2.2 software for the Desire to remove pre-installed Vodafone 360 apps and branding in response to customer outcry that the additions were unwanted and taking up storage space.
Meanwhile, Orange HTC Desire owners are still waiting for Froyo, as the operator said in August that it is waiting to receive the software from HTC. Orange said it expects to make the OS update available to customers from mid-September.