I ask this because of the backward compatability. I have problems and white screens when using 32 bit plugins. Also when loading an old song with 32 bit plugins. 
Anyone else have this problem?

Here are the system requirements:
https://www.cakewalk.com/Support/Knowledge-Base/2007013383/SONAR-Platinum-Professional-Artist-System-Requirements
 
So it's 64 and 32 bit versions...
Thanks..

Platinum will/can install both 32 & 64 bit versions.
 
As a general rule of thumb, if you want to avoid problems, don't use 32 bit plugs in a 64 bit environment.
64 bit plugs will of course not even load/run in 64 bit

Bristol_Jonesey
Platinum will/can install both 32 & 64 bit versions.
 
As a general rule of thumb, if you want to avoid problems, don't use 32 bit plugs in a 64 bit environment.
64 bit plugs will of course not even load/run in 64 bit

Pretty sure you mean 64 bit plugs will not load/run in 32 bit Windows.

Bristol_Jonesey
 
64 bit plugs will of course not even load/run in 64 bit

I guess this is a typo. FWIW, jbridge claims to run 64bit plug-ins in a 32bit host. It is best to avoid bridges if possible.

My first install of Platinum somehow got to be 64-bit. I've only used X1,2,3 in 32-bit. New Platinum could not load old projects with my 32-bit versions of purchased Prochannel modules. No crash, just a dialog that can't load them. Then I loaded the 64-bit versions and rescanned. Still my old projects won't open in 64-bit. Missing step maybe?
 
Also, after I installed 32-bit platinum, I see that 64-bit platinum is not available in control panel -> programs and features to be uninstalled.

scook

Bristol_Jonesey
 
64 bit plugs will of course not even load/run in 64 bit

I guess this is a typo. FWIW, jbridge claims to run 64bit plug-ins in a 32bit host. It is best to avoid bridges if possible.

Yep, typo.
 
Otherwise it just doesn't make sense