osmo not opening

OpenOffice comes default with Ubuntu.
Which Ubuntu version (if at all)?

In case close Osmo.
Open Nautilus (or any file browser)

Go to (hidden) folder
/home/user/.osmo

and remove the lock file.
Start Osmo.

If access is permitted, it might be a permission issue.
To diagnose open the terminal (applications -> accessories -> terminal)
and insert:
ls -al .osmo

All output lines should include your username.

If not:
sudo chown -R username ~/.osmo

Other investigations.
a)
After a failed start of Osmo
open (hidden) file .xsession-errors
Scroll to bottom and look for lines regarding Osmo.
Post it here.

b)
Open main menu (system preferences -> main menu)
Search the Osmo start entry, right click -> properties
Verify the run cmd is: osmo

I am trying lubuntu 10.04
there are lines about osmo in .xsession-errors but all similar. here is a line
(osmo: 29618): Gtk-WARNING **: Failed to set text from markup due to error parsing markup: Error on line 1 char 27: Invalid UTF-8 encoded text in name - not valid '03:05:48 \x81xc3\xdb\xcc'

After deleting the lock file from ~/.osmo osmo opens for few seconds and then closes unexpectedly.

After looking at all the files here, not really a clue which file that should be.
I'd rename the folder .osmo, reinstall and test. If it works you can copy the files successive from renamed folder to new one. You could also try to change the theme and test if it works then.

If nothing helps report a bug there.
http://sourceforge.net/tracker/?group_id=206587&atid=998196

http://clayo.org/osmo/

Good luck.