[CentOS] CentOS/SNMP update breaks MRTG?

[Noob Centos Admin]

Thanks guys for all the suggestions. None of it changed the situation
but I'm beginning to think that it might have to do with SNMP not
accepting word names in MRTG, or more specifically some kind of
language encoding issue.

This is because of the following reasons

1. It's been pointed that out that MRTG need to be started with the
options env LANG=C because it won't work properly if LANG is UTF8

2. On some options I try in MRTG, the log shows some error about Wide
characters returned from SNMP, and I see a chinese character, which
obviously shouldn't be a return value.

3. Addressing SNMP variables by name does not work in MRTG, but works
from command line. e.g. something like ssRawCpuLoad is fine in command
line, but does not work in MRTG config file, only the dot-numeric
equivalent would return some kind of data in MRTG.

4. The problem started AFTER I rebooted the system after the update,
so the reboot might have possibly allowed some settings to take effect
with regards to the server's encoding. Maybe Centos 5.3 went from an
EN_US language default to UTF8 default?

If this is indeed the case, how would I possible change the
interface/shell language settings back to the English one, since I
don't typically need to input non-English characters nor view them in
shell?

I've added a LANG='en_US' and export LANG line in /etc/profile but it
doesn't seem to be doing anything. Do I need a reboot for it to work
like I am guessing based on #4 above?

Thanks!