use of graphics characters recently disabled in xterm

[Theodore Kilgore <kilgota auburn edu>]

I have recently done some upgrades, keeping current with 
slackware-64-current. And what has happened is that suddenly MC started to 
print funny characters around the panels instead of printing vertical and 
horizontal lines. This happens only in an xterm, not in the console 
terminal where all remains OK. The command mc -a replaces the straight 
lines with vertical and horizontal dashes, but that does not look nearly 
so nice.

Oh, I should also say that this happens only on my home machine which has 
an AMD processor and on-board ATI video. It does not happen on the machine 
at my office, which is an Intel CPU with on-board Intel graphics. The two 
machines both run slackware-64-current and as far as I know the two 
machines have exactly the same list of distro packages installed.

The only thing I can think of is that something in the options for xterm 
needs to be changed, but I have no clue about what that magic option might 
be. Or, it could possibly be some library which deals with graphics and is 
somehow broken on an AMD-based machine.

I am pretty much guessing, of course, but to fix the problem would be 
nice. Anyone have an idea?

Theodore Kilgore