I've taken the code from the linear chartview example (
http://demos.telerik.com/silverlight/#ChartView/Gallery/Linear) and added the following to the chart:
The problem is present in this application too.
The version of all the referenced Telerik dll's used is 2012.1.326.1050 (runtime version is v4.0.30319) (Silverlight 5 of course).
Visual Studio version 10.0.40219.1 SP1Rel. .NET Framework 4.5.50131 SP1Rel.
Running on an Intel(R) Core(TM) i5 CPU 750 @2.6HGz
4GB RAM (2.93GB usable)
Windows 7 Professional (SP1) 32-bit
NVIDIA GeForce GT 240