I've noticed this with every single widget I've downloaded. It never happens with apps, just widgets. Apparently, it only affects certain phones. A reboot always makes the widget appear. I contacted HTC about it. Below is the correspondence.
My email:
There is a bug in the Rezound software. Whenever a wiget is downloaded to the phone via the Android Market, it doesn't show up in the list of wigets until the phone is rebooted. This is NOT unique to my specific phone, but all Rezounds.
Their response:
Dear RH,
Thank you for taking the time to contact HTC about the HTC Rezound, RH.
We appreciate your feedback about the Rezound. Unfortunately we were unable to reproduce the issue on our lab devices. Each attempt to download applications and place the widget on the home screen without first performing a soft reset was successful.
If you are experiencing this issue and you have a task killer installed on your device, we suggest to remove it as these may interfere with the basic functions of your phone.
Next, perform a soft reset on the device by taking out the battery and waiting for 30 seconds before powering back on.
We apologize for any inconvenience this may cause. Keep in mind that we are here to answer any technical questions or concerns you may have between 6am to 1am EDST, 7 days a week for your convenience, or by phone at 1-866-449-8358.
Sincerely,
Tara
HTC