UK satellite TV broadcaster Sky last week quietly released a firmware downgrade to fix dozens of old Sky+ boxes rendered inoperable by a firmware update transmitted earlier in the week. PVRs affected include almost all machines equipped with upgraded hard drives.

The original update was sent out in the small hours of Thursday morning. However, some owners of Pace's V1 Sky+ box checking their machines over breakfast found the hardware refused to come out of stand-by mode. Other V1 owners experienced no such breakdown, and it quickly emerged the glitch only affected boxes from which the original 40GB hard drive had been replaced with a higher-capacity unit.

Sky did not respond to our calls for comment, but Reg Hardware readers told us on Friday Sky was transmitting the previous version of the box's firmware. The old code can be reapplied by forcing the machine to perform a system software update - a task otherwise blocked by the box's auto-download code because a later version is running (or not) on the machine.

The 'fix' was later confirmed by other Sky+ users posting on a variety of internet sites, such as Digital Spy.

According to readers who spoke to Sky support staff, the broadcaster initially denied responsibility for any lack of service because the boxes were not standard specification. A fair point, perhaps, but not helpful. Fortunately, the company relented and provided the old firmware to get upgraded boxes up and running again. A few too many threats to cancel contracts, we wonder? Either way, Sky isn't saying.

Readers tell us the procedure for forcing the firmware downgrade is as follows. Proceed at your own risk:

• Switch off power to the Sky receiver at the wall socket.
• Hold down the Backup button on the front of the box and keep it pressed.
• Switch on the power at the wall socket.
• After about 15-20 seconds all four LEDs on the front panel should come on.
• Release the Backup button.
• The TV screen should now read: "Updating System Software. Do not disconnect from mains supply or satellite dish."
• The update process may take upwards of 10 minutes.