The error message that reads, "Our servers are currently experiencing a technical problem," provides a translation into Vietnamese. However, many Vietnamese Wikipedia users will find the translation unreadable, because the page specifies Gill Sans MT, Gill Sans, Trebuchet MS, Helvetica, and finally the fallback "sans-serif" font. The first three all lack the Latin Extended Additional codeblock, which includes most of the characters necessary for displaying Vietnamese text. Helvetica and the standard sans-serif fonts do have the necessary glyphs, but Internet Explorer does not support font substitution.
As far as I can tell, Vietnamese is the only language on that page that requires the Latin Extended Additional codeblock, so a simple CSS rule like:
div#vi {
font-family: Helvetica, sans-serif;
}should do the trick.
Version: unspecified
Severity: normal
URL: http://vi.wikipedia.org/w/index.php?title=-&#Vietnamese