since paying for and installing AVG, malwarebytes seems not to be functioning. The icon is still there and when I click on it it asks me to allow access. Then is says the file is corrupt or unavailable and to re download it.
It could be AVG and Malwarebytes clashing. Are you trying to run them together? AVG could see Malwarebytes as malware and is blocking it. Try turning off your AVG temporarily and then running Malwarebytes.
I wouldn't have thought that AVG & Malwarebytes would clash. More likely to be that Malwarebytes wishes to up-date to its latest version. Hopefully you have been using the Free Edition. If so, download the latest version.