It shows that it still unconfirmed transaction in the blockchain.info
0.5.17 version of multibit classic
I was going to change from multibit classic to hd but after i noticed about the link you posted for update then i tried it and it shows that it is confirming in the wallet with a shaded circle which is going to complete now. Thanks!
Does your version 0.5.17 have a fee slider like the one shown in this quote? I know version 0.5.16 doesn't, but the latest version does. The network is overloaded and most of the time transactions need a high fee to get confirmed fast. Even with that slider on maximum fee it's not enough at the busiest times.
I'd upgrade to the latest version of classic.
The latest multibit classic (0.5.19) has a fee slider in the preferences. It's maximum possible fee is 0.0005 BTC per KB, and there are times when that's not high enough to get a fast confirmation. This is a screenshot of it.