The problem could be connected with .ini file created by blast.
Here's a letter of user who faced clast crash problem:
"Today Ugene crashed 30- 40 sec after opening I did not try to do any thing.
But I made it to work when I removed my comodo firewall. Blast also had
problem of initiating which was corrected by removing 'Biolign' (ncbi.ini)
Now its well and fine.