Resharper 6.1 not working with visual studio 2010

Resharper is working for projects in a VS solution, but not working for other projects in a different VS solution. The example of the problems are below:

* These are greyed out in the context menu: "Go to implementation", "Go to Declaration", "Find Uages", "Find Usages Advanced ... "
* ctrl-T  -> enter type that I am looking for, but returns nothing, even the type is within the VS soluion.

The test above has all files available within the same VS solution.

I tried each of the steps below but not working

1) deleting the folder for Resharper, e.g. _ReSharper.XXXX, and files (xxx.sln.docstates.suo, xxx.suo)

2) http://resharper-support.jetbrains.com/entries/23853492-ReSharper-stopped-working-for-a-single-specific-solution

3) Magage Options -> Reset All Settings -> restart VS -> working, but restart again, and NOT working again.

After I closed VS, the VS windows disappears, but it still hangs in background, which I can see in Task Manager.

Is there any more settings I can try to fix this?

Thanks in advance.