Controls does not exist in current context when building the project

Help, does any one knows how to get rid off the intermittent compiling error message?
Error 290 The name 'lblAddress' does not exist in the current context C:\webwork\Meds\RxForms\RxFrm.aspx.cs 37 
The above mentioned error does not always occur everytime I re-build or build the web project.
Please note that the above mentioned error is not real but it is annoying the control lblAddress does exist in the context (RxFrm.aspx)
and it is propered called in the code behind RxFrm.aspx.cs also when the page is called via the IIS/web works fine.
Development Environment
Windows XP Pro Service Pack 3 or Windows 2003
Visual Studio 2008 Standard Edition All SP applied
.NET Framework 3.5 SP1
TIA
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