Dont laugh, but I just changed my bike from a mtb to a road bike. (Thats not the funny bit =) )

Anyways, it has shimano 105 sti (9 speed) shifters.

One problem is that almost every gear shift is messy, either taking an age to move gear (if it decides to at all), making a lot of noise in the process or jamming up to an extent, Ive even managed to knock the chain off when trying to shift the front cogs. Its a new bike so it should be set up properly and its is clean. Any ideas whats up...its not a cheap bike and compared to my cheapo mountain bike its put to shame, which just isn't on. What are the likely causes for all that?

OK. Now for the stupid part =)

Ive noticed that on these shifters there are two small buttons, I have a feeling these might switch off the shifters. Is that right? If so, whats the point in that? Where they are positioned means I keep pushing them by accident when I change my hand position on the handlebars. Locking myself in a stupid gear and unable to get my shifters to work again.

My bikes in the garage as I type this and the rear shifter isn't working but the front one does. Ive pushed the buttons several hundred times but nothing happens.

This has happened before, and they've come back to life as mysteriuosly as they've died...WHATS GOING ON!!!

Any help greatly appreciated.

Many thanks,

Serpico.