Although quite a while has passed since Microsoft released the Service Pack 1 for Windows 7 many users still may have problems with installing it. This is especially troublesome if you have formatted your hard drive and you want to install a fresh (update-free) copy of the operating system from your system recovery partition.
The main cause of the problem is usually with how Service Pack works. You can think of it as a brick wall, with each of the bricks as a separate update. Unfortunately, by taking out one of the bricks (an installation error) the whole construction collapses.
Instalation errors may be caused for example by too little free space on your hard drive, an unexpected shutdown of the computer during the setup, a conflict between the update and some software, a malware infection, errors while reading files from the HDD, or registry errors.
If we are not able to install Service Pack 1 you should first check if any of these situations doesn't take place. To reduce the risk of getting any problems you should install Windows updates right after finishing the operating system's setup.
If it does not bring any results, you should go to the Control Panel and click on the Troubleshooting module in the System and security section you can find Troubleshoot Windows Update. A simple wizard will launch that will analyze the causes of errors and remove them.
Another idea is to download the Service Pack 1 from the Internet on your own and install it as a normal program. Although this procedure may be a bit less comfortable, it does not require you to install the Windows Update feature that is sometimes quite unreliable.
The last possibility is to use a system tool called SFC. To use it you have to launch the terminal ([Windows]+[R] or cmd command) in the administrator's mode. Later you have to type in sfc /scannow
At this moment Windows can ask you to insert the installation disc. If you have a hidden system partition on your laptop, then your operating system will probably copy the necessary data from it without any work on your part. SFC will scan all the Windows files and resolve the issues automatically.