HELP! Illegal operand error - can't open file! (v.2)

I have a file that I've done about 40 hours on since last duplicating it. It's been saved multiple times, and successfully. Now, however the file seems to be corrupt. I'm getting the following error message when opening it:

Can’t open the illustration. The illustration contains an illegal operand.
Offending operator: “((((((((((((((((((((((((((((((((((((((((((((((((( (((((((((((((((((((((((((((((((((((((((((((((((

After i last closed the file, i've defragged my hard drive because it's been sluggish. Ive also deleted a couple of random temp files that I'm now thinking may have been in regards to the Ai file. Does anyone have any ideas on what i can do to open this file (preferable) or anything else?
Thanks in advance for any help or info you can provide!
Ben
(ps-this is my second posting of this - frantically trying to fix this and didn't pay attention to what i was typing. i forgot to mention a few things so i just resubmitted rather than constantly adding messages. thanks for understanding

Ben,

Corrupted files are difficult. The first and simplest thing to try is to place it in a new document.

well, I've tried opening it, placing it in multiple programs and can't get it to even open. any other ideas or do you know of a way to "force open" it or something? This is on a PC by the way, if that makes a difference.

Ben:

Jacob suggested that you make a new blank document in AI and then File> Place the old .ai document into it. Did you try this?

steve

Hi Steve, when shall we be going nuts, or rather acorns?

hi steve -
sorry about that - i had replied to your email yesterday and i guess it didn't send. Anyway, yes, i had already tried this. I tried placing it into a blank page and it gave me an error saying it had no PDF content - wouldn't place anything. I've also tried placing it in other apps as well. any other ideas?

Hi all,
I'm having a similar issue - layers are missing now. I'm using Illustrator CS3 on XP. I saved my file (often!) yesterday but today when I opened it I got:

Can't open the illustration. The illustration contains an illegal or misplaced operator.
Offending operator: "U"
Context:

U
% /ArtDictionary:
%;
%
9()XW
U

I've tried placing it in a new file, opening with older versions of Illustrator, as well as Photoshop, etc. One thing I haven't seen mentioned elsewhere is that if I open Illustrator, and File->Open, the whole layout appears in the preview window (including the missing layers).

Thanks all,
mike

This would be one for Teri.

We are having similar problems in one of our labs at school.

Can’t open the illustration. The illustration contains an illegal operand.
Offending operator: "BRK/Stranded-(BRK 0 0 0 TZ
%Al3_EndEncoding True Type
%Al55J_Tsume: None
%Al3_BeginEncoding: _Submarine Submarine
[/_Submarine/Submarine 0 0 0 TZ
%Al3_EndEncoding True Type
%Al55J_Tsume: None
%Al3_BeginEncoding: _Swiss911BT-Extra

Any suggestions?