Missing Method toString

[Guest]

Hi fellows:
I´m having a strange situation.
I´m getting an exception "System.MissingMethodException".
Method not found: System.String
Hipernet.Framework.Web.controles.wcTextBox.toString().
The class pointed to is a custom Web Control class that inherits from
another custom Web Control.

The parent Web Control overrides the defaul toString method.

It´s very strange cause the is no compile-time error.
The error apears only ocasionally, and it gets solved by recompiling the
whole solution. Sometimes the error disapeears after the first recompile,
sometimes after the second, sometimes after the third....

Recently we discovered that the error appears after meking a "Re-Build
Solution" but not after "Build Solution"

How can the "toString" methos disappear??

Thanks in advance

Sebastián Streiger