It isn't clear if these problems are AVG problems or Windows problems.
If AVG, then I would use System Restore to return the system to a time and date before you installed AVG.
I run Windows 7 Professional 64bit & have recently added AVG to my system (cannot activate) and since attempting to add, have received numerous error messages which no one can assist me with. for e.g.:
Error 1935 assembly microsoft .VC90.ATL,version ="90.30729.414B"
Processor Architecture = "x86"
HRESULT = 0X8007054F
MSEngine failed to install product unrecoverable error 0XC0070643
Root cause found Integrity check & repair result failed error code =x0490
Please can someone assist me.