So a few tips; don't change your dynamic memory limits to such high numbers. Sketchup can only access up to 3.8/3.9 gigs of ram (3800/3900mb) before it crashes. Its still a 32 bit program, and we have to work inside those 32 bits.
The dynamic memory limit is measured in megabytes not gigabytes or kilobytes. So when you use large numbers, like what you're putting into your dynamic memory limit, you're not actually helping your rendering speeds. If you set it to 0 its automatic and V-Ray will figure it out on its own. By default its set to 1024, so its a little slower, not noticeable in small renders, but more stable with larger ones. I'd suggest changing it to 2048, or 3072 if you would like to access more memory.
The next thing I would suggest you try doing is using the 64-bit workflow to prevent large, complex scenes from running out of memory. When running this method, set your dynamic memory limit to 0. See the attached PDF Document for more information. The 64-bit work flow, along with other helpful tutorials can be found on help.chaosgroup.com/.