Hi Mark See,
Thank you for your question. We have a page on the problem: Having troubles opening the CHM file?
Basically, try the following two things:
1) Copy the *.chm files to your local hard drive if you access them over the network.
2) Right click the chm, click properties, and then click the Unblock
Do not hesitate to contact me back if this does not help.
the Telerik team
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