Update Fails After Hard Drive Replacement

My Dell 1525 Windows 7 laptop had begun to experience more and more frequent hard drive errors. So, in an effort to fend off total disaster, I purchased a new hard drive. The new drive was slightly larger than the old one (250GB vs 160GB). With a week old backup in hand, I used Acronis to do a disk CLONE to the new drive in an external enclosure. I was able to do it without any apparent drive errors. I then swapped drive for drive and rebooted. My most frequent apps worked fine, network access was fine, etc. Then I went to do a Windows Update - not fine. The little shield in the upper left corner of the box was red and, when I clicked on the "Check for Updates" box, it replied Windows Update cannot check for updates because the service is not running. You may need to restart your computer." I went to Services, started the service, marked it Automatic, and tried again - no joy. So, as it suggested, I rebooted. No joy again. After trying a couple of different backup versions with the same result. I went back to square one and used the original Windows 7 install disk. The install went fine and I was able to use Windows Update successfully. I hoped that having verified that a vanilla Windows 7 worked, I might be lucky enough to just be able to restore my latest backup. Wrong. The system appears to work fine with the only KNOWN problem being Update - there may be other problems, as yet unknown. Differences I am aware of: new hardware partitions proportionally larger than the previous disk.