Thanks a lot for such quick replies, and sorry to take so long to get back - in between I could not access the concerned computer. Oddly enough, though, now there seems to be no problem

. I did not use the linux-tui method, but instead used vasm to allow me to boot into text mode, and then edited my .xinitrc to run startlxde to test it out. To my surprise it seems to be working. In addition, XFCE - which I had installed from the repo - also now seems to be working after some initial troubles.
Thanks again and will let you all know if I face further LXDE issues...