where's Corral Canyon? Is that a green, blue, black trail? . . .
Corral Canyon is a Federal OHV area (National Forest Pass required) in eastern San Diego County, not too far from Campo. It sounds like this incident occurred on the Espinosa Trail, which is not actually in the OHV, but runs from the top of Los Pinos Mountain down to the road that encircles the OHV. Espinosa is a fun trail - I don't know what green, blue, black means - someone else will to answer that. I can tell you that the couple times I've run it I've not made contact with my sliders or skids, but was glad they were there. Good A/T tires and a bit of lift make a big difference. That trail can get really eroded in spots. Others times it's not too bad. Last time there was a fallen tree with a rather steep approach bypass carved around it.
I think the last time SCCX ran this as a club was in July of 2006. Starting the next day it was closed for a few years due to a large fire (the Horse Fire) and subsequent time needed to restore the area.
Here's a shot from 2006 that I think was at the same spot as the incident, from the pictures shown. This is looking up the hill in the other direction. I think my Xterra was pretty stock in those days.

The SCCX picture thread from that run went away when the old website crashed, but here is a link to my personal gallery of shots from that trip. It's a fun trip, but we probably could have picked a cooler day - it was about 100F, and humid. After a fair number of u-turns we finally found our way to 4 Corners, then took the one-land paved shelf road to the top of Los Pinos Mountain to visit the fire lookout, then took Espinosa back down to Corrall Canyon Road.
http://frankbaiamonte.smugmug.com/So-Cal-Club-Xterra-SCCX/Corral-Canyon-Espinosa-Jul/I went back again in July of 2010, not long after it re-opened, with some friends in their Jeep. Here's the start of Espinosa just after leaving the fire lookout. It's pretty much all downhill from here.
I think this is that same spot, again looking at it from the lower part looking back uphill.

Fallen tree.

Here's a link to my gallery of pictures from that day.
http://frankbaiamonte.smugmug.com/So-Cal-Explorations-Day/Los-Pinos-Espinosa-070310/