The problem started recently. Whenever I try to launch the game, it takes so long time to launch. If I click on resume room and click again in launch quickly, it starts immediately without any delay. However, later I found a small window in background titled 'select patch to continue' and in the list there are 3 different patches that are installed (1.0, 1.3c, 1.4RC etc). If I click on any patch or even cancel the game starts in single player mood. Does anyone have idea how to resolve this issue?

hi
are you talking about playing in a voobly game or off of voobly?
if off of voobly the launcher box allows you to use any of the patches you select and then launches to the game. were you can play in single or muti-player mode [by ip]
if on voobly, check the game tab at the top of the game room. see it is not set to "start in single player"
the launcher box you describe should not show while at voobly.
in the lobby, at the top, options, do the game diagnostic and show here.