I've noticed this too. I had it happening consistently in a lobby on Swiftwater the other night, but I HAVE had it happen in other maps too, though it's much rarer.

I launch with

-novid -nod3d9ex -window -noborder

but I don't use a graphics config, just settings I manually enter.

Here's my config.cfg if it'll help.

Also, Sigafoo had this happening to him on stream on pro_viaduct and Gullywash. He didn't crash, though.

also for those who want to see for themselves what exactly is happening:http://www.twitch.tv/exxtremegamers/v/3934461

nobody got any ideas to fix it without reinstall?

how is reinstalling not one of the first things you try

My tf2 folder is currently 30GB sounds like fun redownloading all of this and just have hope that it will fix the problem.

Run less extreme graphics settings, maybe run -dxlevel 90 instead of -dxlevel 98? I noticed something similar to this the first time I tried to run 144hz and joined a barnblitz 32 player pub. Props and people disappeared.

http://www.ugcleague.net/forum/showthread.php?33768-Crashing-on-Swiftwater/page2
http://teamfortress.tv/thread/22657/props-disappear-then-i-crash

There are many potential solutions across both threads, have you already seen/tried them already?

I'm on 144Hz, but I'm not running dxlevel98 because I've heard of similar issues.

First thread debunks the suggestion from this thread that reinstalling fixes it. It doesn't. It then goes on to state that mat_hdr_level 2 might cause it; mine is at 0. That's the only helpful advice from this thread, besides someone saying changing configs helped them. I don't run configs.
Second thread gives no valid suggestions, because viewmodel_fov is now clamped to a valid range. In fact, that thread ends with further complaints that it's happening again and no fixes.

Wow many potential solutions, and literally all of these you could have determined don't apply to me because I posted my entire config.

Being able to use Google is not a replacement for common sense.

i also had crashing on barnblitz and swiftwater. i used to have cl_new_impact_effects set to 1, which i noticed you have, and i stopped getting disappearing props or crashes after i set it to 0. i'm not sure if it'll help you but that one command worked for me.

Thanks everyone for the help.
Most of the posts that i could see ppl were using high graphics either with cfg's or not but still in high im gona try run the same cfg with both cl_new_impact_effects on 0 and mat_hdr_level on 0.
Will post results later.

Ok good point dude next time I won't try to help. Also wasn't aware that you were the original poster of the thread, or that you were the only person having this problem. I guess you're right though, I specifically quoted you, so it follows that the post was specifically directed at you and not at the general public. Furthermore, you're 100% right, everyone's first language is English so they can easily word their problems in English so as to find solutions to problems on English-speaking boards! It's not like 90% of the question threads here can be solved by googling or anything...

Are you having a bad day?

Just posting an update for future ppl that may have this problem it seems disabling those two cvars i posted above solved the problem.
This game is too old to be running in high settings it seems. Kappa

gotta have to try this, thanks for the update