it seems that often times a rapid onset of numerous computer errors is related to:
low voltage at battery (check when powered off, check when running at idle if possible). easy to replace
check brake lamps and brake pedal switch
if you decide to replace the battery, that's a GREAT time to pull the plugs and inspect the TCCM, it lives right behind the battery. it's kind of a chore to get to, but inspect the connectors for corrosion. also not uncommon for water ingress to foul that up. if you see corrosion, the ECU right behind it should also be checked.
i just bought an 06RRS which was sitting on stops, and randomly (not every time) was throwing all sorts of errors including HDC, EPB, ABS, ATC... and many similar codes.
i bought the nanocom EVO and have been happy with it
next, check for corrosion under the FL and FR kick panels and door sills.
i ended up replacing my ATC module (which is actually attached to the ATC buttons on the console, they are all one unit). it turns out it was a scrap yard part to begin with, and looks to have had a latte unloaded into it.
the EAS (air) system is funky and appears to deactivate itself when the ATC and VDC aren't working properly. which color is your suspension warning light, orange or red? does the message center give you any info about the air suspension, and do you have the 4x4 display?
2003 Disco 2 SE7 - going to be buried in it
2006 RR Sport HSE - project
1997 Disco SE - SOLD
2003 Disco 2 SE7 - SOLD
1995 Disco SE - SOLD
2001 Disco 2 SE - SOLD
Foxwell NT510, Nanocom EVO