The i81ctrl.dll file is part of AsusDesk Dynamic Link Library by Asus. Asus makes a wide variety of computer hardware. They make everything from motherboards to full computers. The i81ctrl.dll error is a standard registry error. However, you do need to check its legitimacy.
While Windows DLL errors are common, attackers know this as well. Some attackers will disguise malicious files as a common dll error just to get it on your computer. Other less reputable companies will offer free scans that detect these fake registry errors to sell you software for removal.
You do not have to worry about fake scans with ZookaWare PC Cleaner. ZookaWare, the creators of ZookaWare PC Cleaner, is a member of the Better Business Bureau. They back their software up with a 60-day money-back guarantee and a 100% error removal guarantee. If ZookaWare PC Cleaner does not get rid of the errors the first time, let them know. Their team will get you a solution within 24 hours or your money back.