Here are some random ramblings from me
If you are using Gotham nightlies (ie Alpha releases) it's always worth keeping that in mind, it wouldnt be the first time that weird alpha/nightly issues are contributing to things. You could try running older and newer nightlies as well as a troubleshooting step. You could also list the precise nightly, so krusty or others could attempt to duplicate your exact setup.
Why dont you temporarily try the Frodo XBMC (with correct pvr.wmc addon version for Frodo) and see what happens. That should help narrow down whether the Gotham build is related or if it's a server/remuxing issue
Krusty - I do think in the past when I was mucking around with the remuxer I did manage to crash XBMC but that was potentially by having breakpoints in the server side and all sorts of things... It was a while ago so I really cant be sure though.
The crash is one thing, but "things slowing down" also sounds like it could be worth investigating the angles of storage/processing being impacted etc. Certainly not trying to point fingers and your setup sounds more than adequate (im running mine on a pentium processor, with a ISCSI mounted rec TV drive on a NAS over GB ethernet so yours is far more powerful than my setup!) but just thinking of how we could potentially isolate/troubleshoot things.
Out of interest, Is the recorded TV hard drive dedicated only to recorded TV? do you have anything like SickBeard/CouchPotato or NZB stuff that could be hammering disks while unpacking archive files and things like that?
If you are able to, you might try some different storage arrangements to see if it made a difference (eg a hard drive that wasnt so full, or an SSD for a shotgun approach (not recomending to use an SSD forever, just to see if it made any difference).
You can also take the WTV file and the TS file and try playing them back through XBMC normal video section and see if they play OK. They probably would I guess, although it might be interesting what happens when you get to the very end of the TS file (perhaps it might crash out, like it did when it was watching this TS file as a "LiveTV"). You have uploaded the WTV files but perhaps upload a TS file as well since that is what your remuxer has produced from the WTV file. If krusty has tested remuxing your WTV files and not had the same problem than it seems to indicate that it is something that is happening during remuxing on your PC that is upsetting XBMC, and not something in the WTV file which is reproducible when remuxing that WTV file.
If you dont use PVR function in XBMC does it ever have any lags/slowdowns or hangs?
Do you have another PC/laptop you could run a client on and see if the same problem happens?
Also another option is to setup another PC as the server, with both a local client and using this existing client, and seeing if either of them crash/slowdown. Obviously this is a bit painful as you need to have WMC on the other PC, setup the channels, move your tuner over etc. It depends how far you are willing to go! I guess leave this one until last
Also, we could seek help from actual XBMC developers regarding your error logs. Just looking at the 2 you posted and they show different error messages. The first one had errors loading a shader and creating a video texture, whereas the second one seems to complain about "timeout adding data to renderer".
I (and I assume Krusty) really have no idea about this side of things so we really dont know what is happening. It seems logical to conclude that if it only happens when watching TV it is something in the TS file that could be doing it, but it could be as simple as problems on the backend creating/remuxing the data are causing the frontend (nightly Alpha builf of Gotham) to crash, when Frodo might have handled things more gracefully and just stopped the playback... I am not saying this is the cause, just saying such a situation could be possible, and we need someone who knows what they are looking at to review your XBMC logs and comment.
