Question Regarding Multi-Table tournaments

[unc90]

Hi,
I'm new to this forum and had a couple of questions I was hoping someone could help me with.
I've been playing online (and when I go to Vegas) for roughly 2 years. I've kept an excel spreadsheet and have made good money over this time span and corrected alot of my mistakes (i.e. calling in early position w/K,Q, A,J, etc,...).
Where I'm having trouble at this point is w/multi table no limit tournaments. I just started playing this week in these types of tournaments. I've played 2 so far. Last night, there was a 589 person tournament at Ultimatebet.com and I finished 166th.
Where I lost big was on 2 particular hands.I raised preflop in late position w/AK. An A,K, 6 came out on the flop. I made a big bet and someone came over the top all in. I called w/ 2 pair. I just felt like I couldn't not call that bet. Well, the other person had a pair of 6's underneath. Did I make a mistake here? This didn't wipe me out but came darn close. I built my stack back up to roughly 1000 chips and I noticed when I was in the big blind, the big stack always raised me. Well, I had K,8 of diamonds. When he raised, I went all in and he called w/ a K, 4 (he was the big stack at the table). Wouldn't you know it, a 4 came out on the flop and I was out of the tournament in 166th place.
Today, I played in a 160 person NL tournament and finished 39th place. I played very conservative until blinds got to be 150-300. I had roughly 1000 chips left and went all in, in middle position w/ 10,10. Someone in late position called w/ 9,9. A 9 came out on the flop and I was done for again.
Am I making bad decisions or am I getting bad beats? I can't quite figure it out. 3 big losses in 2 tournaments has me wondering if my decision making has been correct.
Also, when I look at the players that are in the top 10-20 positions, they have huge stacks after the first hour. It seems my rock solid strategy will have trouble against these huge stacks. I played solid yet conservative. If you had to look at my play and compare my betting strategy to one of the pros, it would probably be closest to Dan Harrington although he's a helluvalot better player than me admittedly. Any suggestions or thoughts would be greatly appreciated.

Regards,

Joe McKinney

[Richie Rich]

Try posting this in the Multi-Table Tournament section for good responses (...this section is for ring games)