Besides most Adobe programs wanting to be located on the system drive, there are other files that have to be located there.
This is one of the limitations with small SSD system drives.
I would suggest filing a Feature Request, to have the Adobe programs located onto other internal HDD's.
Its common practic to install everything on the C drive
If one cannot install on the SSD drive which happens to be the C drive, its not a limitation, its just bought to small.
Strange thing is, CS5.0 worked just fine on a similar setup system, they mucked something up with the 5.5 version.
> CS5.0 worked just fine on a similar setup system
Actually, it didn't. Here's a technical support document that gives an example of something that went wrong if you installed to the non-default location.
Though I agree that you should be able to choose where to install, the truth is that you'll have better results installing to the default C: location.
Please, do file that feature request or bug report. The folks who recieve those need to know how many people this is affecting.