A faulty update for BitDefender anti-virus software has caused chaos for many 64-bit Windows users.

Instead of protecting systems from new malware threats, the update – issued earlier this week – decided to detect a number of essential Windows files as a Trojan virus (trojan.fakealert.5) and wipe them in the process.

This meant that some executable files were wiped, forcing some unlucky users to do a full re-install.

BitDefender has issued an apology over the gaffe, saying on its blog: "We understand your disappointment, we have solved the problem for many of our users already and we are continuing to work relentlessly to rectify the problem for all users still affected."

But, it seems that it is not just BitDefender users that are affected. TechRadar was contacted by an owner of BullGuard anti-virus software (a UK-based company) which utilises BitDefender and it seems there are big problems for its users too.

Its forums are ablaze with angry comments from those affected by the update, who feel the company isn't doing enough to sort the problem out.

Trying to help users

BullGuard, like BitDefender, has issued an apology on the forum stating: "We apologise for this issue that you are experiencing on behalf of the BullGuard update released yesterday for Windows 64-bit systems.

"The faulty update has been removed and we are trying to help all our users that have been affected."

But this hasn't appeased the masses. Even an offer of a free subscription hasn't helped, with one member noting: "I think it is laughable that Bullguard are offering subscription to their software as compensation for all the problems their software caused."

TechRadar has contacted BullGuard and asked for them to tell us exactly how it is dealing with the problem.

Despite the update issue, It does seem that the company still wants to use the BitDefender anti-virus engine, explaining on the forum: "Based on BullGuard's own evaluations and evaluations done by external parties we have and still see BitDefender's anti-virus engine to be the best one in the market and we have still trust in BitDefender."

It did say, though, that it while it currently relies on BitDefender to test all updates, it is "in dialogue with BitDefender on longer term actions to secure a similar situation cannot happen in the future".