fail to start graphical interface

Hi, I'm using Linux Mint 14 and have faced the following problem recently:

after removing and installing some of the software (torchat and LibreOffice to be exact) and rebooting I found myself not being able to log into my system.

first thing I noticed was simply a console line offering to enter my login and password, after that it greeted me with

bash: /usr/lib/git-core/git-sh-prompt: No such file or directory

all my attempts to run startx resulted in nothing but a black screen with an active mouse arrow

briefly serfing the net I've found that installing mdm could be a possible solution, however, after I did that, I've started logging into this very black screen immediately, skipping any time in console

so the only way to get to shell is to drop there using the recovery mode

when I try to launch startx there I get the following message

Fatal server error: Could not create lock file in /tmp/.tX0-lock
xinit: giving up
xinit: unable to connect to X server: Connection refused
xinit: server error
xauth: error in locking authority file /root/.Xauthority

also I can't remove or install anything using this shell due to blocking issues with /var/lib/dpkg/lock and being unable to write anything in /var/cache/apt/

I'd appreciate any suggestions about working this mess out. Thanks in advance