You MUST be kidding me!

[ario <..hidden..>]

Boys! What are you doing to me!

I wanted to process a payment.
So I go to 'Cash|Payment', give a 'Vendor Name' and click Continue.
Ok, there comes the list with 600 [sic!] (see what's coming??) payments
due.
I select ONE payment, open the drop down, select the check box following
the 'Source' field and click 'Update'.
Ok, nothing happens (after all this is 1.3.29), so I click on 'Post'!
BAM! 600 transactions paid! Disappeared! 
No! Not paid! Just disappeared, lsmb THINKS I paid them.
wt.?

You can't be serious with this.
In the previous lsmb I used checking a checkbox meant paying THIS ONE,
not all! 

<despair>
Oh man... 

.
.
</despair>

So, now what?

Is there any way to roll this back?
Or do I have to re-install lsmb, import the latest backup and re-enter
all transactions after the last pre-backup session?

Thanks for this exciting experience :)