Sorry to hear you're having problems. There are a couple of things you can check. If you go into the Tools menu then the add-in manager, You should see the ANTS add-ins, and the Startup check box should be checked. Is this the case?
Also with the ANTS 5 menu, some of the menu items will be disabled if there is no project loaded. Are you seeing greyed out options if the projects are open?
If you're still having problems here is a knowledge base article which you might be able to use to solve the problem:
http://www.red-gate.com/supportcenter/C ... spx?p=ANTS
The article refers to version 4 so you'll need to update the assembly references with:
regasm /codebase "%programfiles%\\red gate\\ants performance profiler 5\\RedGate.Profiler.Five.AddIn.dll"
regasm /codebase "%programfiles%\\red gate\\ants memory profiler 5\\RedGate.Memory.AddIn.dll"
but a quick word of caution, this will reset all of your visual studio add ins.