I am afraid that we are not familiar with such a problem related with the RadListBox. which is why we would need to replicate it, so we could try to pin down the reason for it. Unfortunately, after different tests, using the provided code-snippet, the problem was not replicated on our side.
Since such problem might be caused by side factors, e.g environment where the control is implemented and so on, I would like to ask you to provide us with an isolate sample, where the problem does resides after the mentioned iis reset.
Also, could you specify whether you have observed such visual defects with our controls on your page? In addition, do you experience any js errors on your page?
I am looking forward to your reply.
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