Can't open the illustration. Could not complete the requested operation.

Sarah,

Sarah,

I believe You may have a file corruption.

Onething often tried first is to create a new document and File>Place the (PDF contents, if any, of the) corrupted one to see how much may be rescued that way.

Here are some websites where you can see whether it can rescue the actual file, and if it can, you may pay for a subscription to have it done,

http://www.recoverytoolbox.com/buy_illustrator.html

http://markzware.com/adobe-software/fix-illustrator-file-unknown-error-occurred-pdf2dtp-file-recovery/

http://www.illustrator.fixtoolbox.com/

As far as I remember, the first one is for Win and the second one is for Mac, while the third one should be for both.

Here are a few pages about struggling with it yourself:

http://daxxter.wordpress.com/2009/04/16/how-to-recover-a-corrupted-illustrator-ai-file/

http://helpx.adobe.com/illustrator/kb/troubleshoot-damaged-illustrator-files.html

http://kb2.adobe.com/cps/500/cpsid_50032.html

http://kb2.adobe.com/cps/500/cpsid_50031.html

http://helpx.adobe.com/illustrator/kb/enable-content-recovery-mode-illustrator.html