Slurs between full measure notes in 7/4 aren't played correctly

"In first two measures, when I don't connect strings with a slur, those two notes are played correctly. When I try to connect these two, playback stops playing them after first measure."

First of all, you need to understand the difference between a slur and a tie. Glossary definitions:
Slur
A curved line over or under two or more notes, meaning that the notes will be played smooth and connected (legato).
Tie
A curved line between two or more notes on the same pitch to indicate a single note of combined duration:
-- Quarter note + Tie + Quarter note = Half note
-- Quarter note + Tie + Eighth note = Dotted Quarter note
-- Quarter note + Tie + Eighth note + Tie + 16th note = Double Dotted Quarter note

Your score uses ties throughout, and you can check this by selecting each curved line (slur or tie) to see its type in the Status Bar (at the foot of the screen). The effect of a tie is is to combine the tied notes so that the instrument sounds continuously for the entire duration across one or more ties.

In MS 4.0 there are shortcuts to add a slur or a tie from the selected note to the following note:
slur = S
tie = T

All's well that ends well. ;-)