I never had this problem in Morrowind or Skyrim so such a thing bewilders me.
It's not inevitable. More information could help forum goers help you troubleshoot.
You say "heavily modded" and that you have played (and I assume modded) Skyrim and Morrowind. So, let's just start by asking for your basic Oblivion game configuration:
Load Order, preferably from Wrye Bash
OBSE plugins loaded
Bashed Patch configuration
Welcome to the forums (that is, if you're really as new here as your profile suggests)!
Cheers.
Sounds like you save via menu? I recommend saving via the console, giving each a unique descriptive name. You'll eventually need to delete or archive old saves, but it's a small price to pay. Oh, and disable any quick/auto saves if you have not already done so. (There are, I believe, a couple of mods that provide save alternatives. I never found it necessary to bother with them.)
Course your problem might be due to a faulty mod, a fault install, conflicts, or some other reason. In that case console saves won't help. Still, you have nothing to lose by giving it a try.
-Decrepit-
Thanks (but I'm not new - I've been here for several months actually )
I have tons of mods installed for Morrowind and I'm pushing its very limits but the only problem I got was random freezing (which stopped after removing a faulty mod). I'm pretty far into Skyrim and all my save games load without hiccup - the only problem I had was the DB storyline not starting (which was resolved by disabling all DLC for some reason)
I do save via console and constantly put the other earlier working saves in an "archive folder". It does not eliminate the issue but reduces the probability of it occurring.
My load order is:
The OBSE plugins loaded are:
I haven't merged anything in the bashed patch though BOSS says that I can merge two plug-ins from that list.
A shot in the dark here, but the only thing that stands out about your load order are all the huge new land additions. Someone with more knowledge than me will have to chime in (I don't play with those mods), but could they be the source of your troubles? For instance, do they dramatically increase the size of your saves? Does this increase the chance of errors while writing the save? Are any of them known to be problematic? Etc....
Good luck!
EDIT: Have you checked any of the options when building your bashed patch?
The problems started way before I installed Unique Landscapes and Silgrad Tower. The only mods which I installed right away were Morrowind_ob.esm and the Elsweyr mod. And my latest working save file is 5.24MB so I believe that it is a normal size (and Bash found no save game bloating on any save files). And no, I haven't built a bashed patch.
well, Morrowind, Anequina, Hammerfell and Skyrim were the main ones I was referring to. I would start my investigations there. But, again, I've never used any of those, so I don't know.