I did some remodeling in my living room (tore out a wall to open it up a bit) and decided that I needed some more light. So I installed 3 recessed lights going down the middle of my ceiling. I ran these three lights to an existing switch box. I connected the lights in series to make things easier, and then connected them to a dimmer switch. The lights worked perfectly for about a week and then they would only work intermittently. I checked all of my connections, and they were all fine.

After a couple weeks of working off and on, they stopped working all together. So I changed out the dimmer switch with a different style. This one worked for several weeks, but the lights would never get as bright as they once did (they were always running around 50% - even when the dimmer was at it's brightest). Then after a couple weeks they stopped working. Since they were run in series I replaced all of the bulbs - didn't help. Tonight I took the dimmer switch out and hardwired the lights to permanently be on. While doing this I also crawled up into the ceiling and checked all of the connections. The lights came back on, but they are still at that 50% brightness.

I'm running 65 Watt flood lights on a 10kA breaker (120 volts). Will changing them to parallel fix my brightness issue? And should I take them off the dimmer or does that matter?

Do you actually mean that you wired the cans in SERIES or do you really mean 'daisy-chain'? If you wired in series, if you take one bulb out all would go dark. If you did it correctly, (daisy-chain) ALL whites in the line of cans would be electrically connected and ALL blacks the same. Removing any bulb would have no effect on any other light or the level of dimming (with a garden variety dimmer).

If you actually wired in series, yes, you will have problems, they will never get anywhere near full brightness. If you did wire them correctly (daisy-chain) then you have to go back and recheck ALL of your connections. Somewhere something is loose and that can be dangerous. The most common problem I have seen is one conductor that looks like it is captured by a wire nut but it is only barely touching. Check EVERY conductor at EVERY connection. Here is where good, neat wiring technique really pays off.