In order to install IBM SPSS, I had to install "libstdc++5" package. I noticed this bug was happening after installing this package and IBM SPSS. After removing libstdc++5 (not required to use IBM SPSS, just to install it), I didn't experience this bug. However, this all happened in last two days, so it could be that Ubuntu updates fixed the issue.
In order to install IBM SPSS, I had to install "libstdc++5" package. I noticed this bug was happening after installing this package and IBM SPSS. After removing libstdc++5 (not required to use IBM SPSS, just to install it), I didn't experience this bug. However, this all happened in last two days, so it could be that Ubuntu updates fixed the issue.