Is it normal and expected and happens to all?

I have observed myself that, if i go for only tactics trainer and theories for a long couple of days with no play at all, then if i immediately start playing online some 10 mins or 15 10 games, i start making blunders, and it takes couple of games to get back to my original form.

Does it happen to all? Or am i the only one?

All the time.

Although I make blunders, I usually find the reason is a 'brain fart' and not a result of doing tactics and studying theory.

Last game I played I completely overlooked a knight fork (I thought e3 was covered) and lost the exchange.

Mind you, I then sacrificed the exchange again to get two passed pawns, which ended up winning :-P

You are super BorgQueen

That's only the second game I have won after losing the exchange twice ^_^

Pity this site doesn't allow posting of games, some of you might enjoy a good "comeback" :-)

@Borgqueen: May be you can copy-paste the PGN files.

The blunder at move 11 for the 2700 rated Stripunsky yesterday at the US Championship shows it can happen to anyone.

We should see it soon on Chesstempo with a hanging piece tag...

Yes, it's kinda encouraging to see a master making such a blunder!

Here is the "comeback" game I was talking about:

[Event "Interclub A"]
[Site "Adelaide"]
[Date "2012.05.08"]
[Round "2"]
[White "Brad"]
[Black "George"]
[Result "1-0"]
[ECO "D30"]
[EventDate "2012.05.08"]
[SourceDate "2012.05.08"]

1. d4 d5 2. c4 e6 3. Nf3 Bd7 4. Nc3 Bb4 5. Qb3 Bxc3+ 6. bxc3 Bc6 7. Ne5 b6 8.
Nxc6 Nxc6 {cxd5 might be a little better.} 9. Qa4 Nge7 10. e3 O-O {Bd3 is
probably a little better.} 11. Ba3 Re8 {Bd3 here is much better.} 12. c5 Na5
13. Bd3 Nb7 {Just 0-0 is ok here. There is no advantage to push.} 14. Qa6 Qc8
15. Qa4 c6 {0-0 might be slightly better.} 16. Rb1 b5 17. Qc2 g6 18. O-O a5 {
e4/Rfe1 may be a little better, but I didn't want to give black d5 for his
knight.} 19. f3 Nf5 {Bc1 here is ok. Blunder coming -- I simply failed to see
e3.} 20. e4 {Dumbass move.} Ne3 21. Qd2 Nxf1 22. Bxf1 Qc7 {e5 here is a little
better.} 23. Bc1 f6 {a4 here is better.} 24. Qh6 Nd8 25. Bd3 Nf7 26. Qh4 Qe7 27. Qg3 Ra7 {h4
here is better.} 28. Bd2 a4 {My plan here is to swap off the central pawns,
locking the situation and holding the e file with the bishops, nullifying the
rooks. Houdini hates the idea ^_^} 29. exd5 exd5 30. a3 Kg7 31. h4 Qd8 {h5
here is good.} 32. Kf2 {Trying to secure the e file. Trying to make a fortress
that black can't make use of his rooks.} Qc7 33. Bf4 Qd8 {Here, my thoughts
were to try to open the h file and get some play with the raking bishops and
the rook. Again, Houdini hates this plan... and wants to play h5.} 34. Rh1 Rae7
35. Bd2 Re6 {Seeing the danger with Qe7 -> Re2+, I want to defend the e file
more.} 36. f4 Qe7 37. Qf3 {Unfortunately, it basically loses.} f5 38. h5 Nh6
39. hxg6 {If black plays hxg6, I am dead (-5.05)...} Ng4+ 40. Qxg4 fxg4 41.
Rxh7+ {Kf6 is good for black, anything else gives white the advantage.} Kg8 (
41... Kf6 42. Rxe7 R6xe7 43. f5 Re4 44. Bxe4 dxe4 {And the pawns fall.}) 42.
Rxe7 R6xe7 43. f5 Re4 44. Bxe4 dxe4 45. f6 g3+ 46. Ke2 Rf8 47. Bg5 Rc8 48. Ke3
Ra8 49. Bh6 1-0

I know a lot of people who resign, or lose motivation, once they lose the rook, or even exchange it with a minor piece.

At the end, was a good game and you balanced it pretty well, but i think black was a good attacker. What was black's rating?

ACF 1625 or thereabouts... and yes, I thought black was a good attacker too!