Strange linking error at run-time

[iw2nhl]

Hi,
I'm writing a C++ program with Qt4 libs.
When I do a particular sequence of operations, my program exits (but does not crash) with this error in the console:

my_program: symbol lookup error: libqtxml_plugin.so: undefined symbol: _ZN15QXmlInputSourceC1EP9QIODevice

The function is inside a plugin I've written to parse XML files.

That piece of code works perfectly if I call it with another set of operations!

Note that I tested it also on Windows 2000 (MinGW compiler) and asked a friend to test it on a Slackware: none of the two shows the problem.
It seems related only to Debian.
May be there is an error in the new GCC compiler? MinGW and Slackware are using older versions of GCC.
I tried with different versions of Qt4 (4.2.2, 4.2.3 and 4.3.0) and the error is always the same, so I think it is not related to Qt4.

I'm using the standard Debian testing packages, regularly updated.

Compiler:
gcc (GCC) 4.1.3 20070601 (prerelease) (Debian 4.1.2-12)
CPU:
AMD AthlonXP 2200+
Kernel:
2.6.18-4-k7
Code:

Thanks to anyone who can help me, I really don't know what to do!

[~s.o.s~]

Asking it on the QT forums would be more like it since many must have encountered the same issue.

[iw2nhl]

Yes, I'll try also with Qt forums (probably also in the official one http://www.qtcentre.org/forum/).

Anyway I'm not sure it is related to Qt, it seems me a C++ error.