I have been using the Japanese and Chinese IME since the mid 90's. Nary a problem.
1) Windows 7 Ultimate 64 bit
2) Das mechanical keyboard - dual USB connects
Now I have written about 100 pages of Japanese in the past couple of years without a single problem, so I do know how to use the language bar.
After Reinstall of Windows 7
Bizarre Problem: Neither left-click nor right click open the Language Bar. Only by hitting Alt/Shift can I switch between the EN icon (English) and the JP icon (Japanese). But that is all. The language bar does not open, so that I can change settings, input method, output, etc.
The only possible problem that I can see, the only "variable" that is, would be the Das mechanical keyboard. In the past I used traditional Logitech wireless keyboards (membrane/dome switch).
Feel free to tell me I am suddenly doing something really stupid. Not a problem. My feelings have been hurt by professionals.