Ah the old M-Audio PCI cards, loved them back in the day, but there is absolutely NO MORE DRIVER SUPPORT. There hasn't been for maybe 10 years now.
Most likely cause considering both versions of SONAR fail on startup, but I wouldn't completely rule out old graphics card drivers either.
I'd open Device Manager and manually do and On Line check search for driver updates. Even if Windows can find any and you get the popup notice that you are running the latest drivers versions that should be enough digital signage.
Sometimes, just like M-Audio did, actually I believe you'll need to search the AVID driver support page for the older M-Audio PCI card drivers and older USB devices.
But many vendors move old driver installers into a "Legacy" folder on their website so Windows searches for the wrong address.
In which case you'll need to identify components and manually search for them yourself.
Keeping older computers running is very much on par with keeping old cars running, and after a period of time it's no longer worth the time and effort looking for parts and solutions that are simply no longer available.
I think of my old Delta 1010's very fondly like they were my old 1965 Pontiac GTO that could light up the tires for 1/2 a block. Actually I would have been very happy if that GTO lasted half as long as the Delta 1010's did, and very disappointed if my Mustang, which is considerably FASTER, more reliable, and more FUN than a GTO on 10x less gas doesn't last 5x longer.
I think about Focusrite Scarlett 18i20 Gen 2 more as something like, ummm, well, I guess I don't think of it other then being a great sounding rock solid audio interface that shall stay that way for many years to come without giving it much thought. Other than maybe swapping out the aging Octapre MKII for a new Clarett OctaPre with built in compressors and "Air" switchable to Focusrite's legendary ISA preamps, could be nice for stuff like capturing killa chest thumping drums all at once very much like Rupert Neve intended.
Ain't new technology grand??
Oh HAIL YEAH IT IS, but you'll never know how much until you at least try to keep up, and the longer you wait the more you fall back, and the more expensive it gets just to stay in one place.
Yes you can re install the SONAR core directly from Command Center.
But uninstalling SONAR first than reinstalling fresh is usually the quickest and easiest way of solving the many things that can cause these and a plethora of other problems.
I've never heard of any plugins crashing SONAR upon startup. SONAR doesn't even try to connect to any plugins until you open a project whether you have it set to auto scan or not.
Now that you renamed your plugin folders I would highly recommend a Windows Registry clean up and get rid of all the extra dead end search paths.
It's a very good practice to routinely do this anyway to keep your system running optimally fast and smoothly.