Some/most Groups/tabs lost on FF close/open

[GoogleCodeExporter]

Before submitting the issue, please check that your version of TabGroups
Manager is the lastest stable one. (Check it in Firefox Extensions).

What steps will reproduce the problem?
1. close firefox
2. open firefox
3.

What is the expected output? What do you see instead?
I should get the same groups back that were defined on exit but instead random 
(or almost all) groups are gone or some random tabs have moved to new noname 
group. 

I had to make TGM to make backups by timer every 20 minutes and keep 30 so that 
I can always find at least one relatively new, working backup.

System Info:
What version of TabGroups Manager are you using?
2014.12.21.005 (the non-beta lost all groups all the time)

What Operative System are you using? 32 or 64 bits?
64

What version of Firefox are you using?
35.0.1

Are you using any other tab extension like Colorfull tabs, Multiple Tab
Handler, TabMix Plus..?
Tab Mix Plus

Please provide any additional information below and screens capture if
possible.
I just have say 5 groups, total of 80 tabs, then I close FF and open it again, 
there may be ONE group with ONE tab or ONE group with 19 tabs (correct number 
but the name has changed to 'Start') or 
correct groups but in addition one new group 'noname' with SOME tabs from SOME 
other group :o
Sadly very rarely the correct groups AND tabs.

Restoring a backup may fix the problem or then not, it seems they too are 
corrupted very often.

This add-on would be great but currently it is very unreliable so the only 
solution is to make backups A LOT.

Please fix it soon :)

Antti

Original issue reported on code.google.com by [email protected] on 13 Feb 2015 at 4:32