Help unable to attach files in safari

Are you not getting an upload dialog at all, or are the uploads starting and failing to complete, or are you seeing error messages, or what?

As a general thing, make sure you have Javascript enabled in the Safari preferences. Many Web site features rely on it.

 

What (exactly) does the error message say?

 

Are you also running Safari Enhancer? If so, I had the same problem and it was fixed by unchecking the box for deactivating the cache.

 

Any kind of program or tip that claims to boost Internet speeds can also cause problems like this, MTU tweaks and the like are common culprits.

That said, there are sometimes problems with Safari itself, and (assuming no tweaks are in place) a reset will often put things right. More here.

 

Okay, did you check out the MTU as described in the linked thread?

"Lost network connection" can, at times, actually mean just that, a problem with the network connection (network card, router, cabling) anywhere in the chain from your computer all the way back to the Web site. Is there any sort of support Web site at your ISP where you can check for trouble reports? Also, do you have any new networking hardware (especially, but not necessarily, wireless) at your end? Anything at all that may have changed can be suspect.

You can rule out a lot of possible problems by trying a different browser (Camino, Firefox, etc.). That will at least tell you if Safari or something else is at the root of the problem.