No, creating a transaction doesn't mean it gets processed. The problem is that their software is buggy, and has been buggy for what seems like forever. It tends to create invalid transactions that get rejected by the network. The problem was never too bad, so they didn't bother to fix it, until recently it started snowballing due to unknown reasons, and currently as much as 85% of the transactions their system generates are invalid and rejected by the network.

All of the above is fact, what's subject to interpretation is what were the circumstances that led to this issue snowballing. Options to pick from are (1) it happened by accident, and was eventually bound to happen as long as they didn't bother to fix the problem, or (2) they are intentionally triggering the bug to hide a big loss of Bitcoins (stolen by insider / hacked by outsider / lost keys to them / whatever).

Option 2 is why everyone (like me) has jumped to try withdrawing their balance, making it a run on MtGox, and probably making the problem worse. (But if the worst comes to pass, it's better to get 15% of your Bitcoins than nothing)