Spell videoeffects abnormally persistent

[Orocnogu 8]

Hello.

Since the very beginning of my participation in this project I have had this issue, but it didn't actually bother me. Not that it does now, but the closer to endgame I get, the more actual problems I reckon happening because of it. Here's the deal:

As stated in the topic, videoeffects from spells like Frost Nova's freeze, Druid's Hurricane or Roots, various poisonous clouds -- these effects persist for a very, very long time. For example, the Disease Cloud that Scarabs of Zul'Farrak use persisted for more than 8 hours and a server shutdown (i've been in and out of the instance, even re-set it once, but when my group got to the place with a lot of scarabs, there were disease clouds on the ground, visible only to me). I have never experienced this problem with Paladins' Consecration though, however, that may be due to lack of paladin tanks there - the problem occurs in, like, 2-3 out of 10 times.

I have a non-modified English client, downloaded from this site; zero add-ons (and none ever installed). GeForce 950 GTX (drivers updater regularly), Intel i5-2400 and 8gb RAM (if that's of any relevance). Video settings set on maximum, 1920x1080 windowed mode, all sub-options checked except Smooth Shading, Vertical Sync and Smooth Mouse.

If this is a known problem, I would appreciate a solution. If not - I am prepared to give any additional information on this peculiarity (in Russian or in English).
Thanks in advance, would appreciate any andwer, although there's no rush since the problem is mostly cosmetic at this point of my gaming experience.

[Orocnogu 8]

I'm deleting the folder on regular basis (like, once or twice a week), it's not "read only", etc.etc. That would be too simple.

[Orocnogu 8]

So... erm... is there an actual fix? I'll take the guidelines into consideration, thanks

[smokeit 26]

Delete and reïnstall the game, preferably to another location, update vidcard drivers.

[Orocnogu 8]

The game client is not "installed" per se, it's just downloaded and unpacked from .zip archive. And I specifically pointed out that I am updating graphic drivers regularly.

Will try this advice in a day or two, then report the result.