|You definitely DO NOT need to install SP2 updates before installing SP3 updates when you already have SP1 updates installed. |
The most frequent reason SP3 updates don't install properly, or cause you problems after they are installed, is because of interference from the resident modules of anti-malware software you have installed.
NOTE that sometimes the resident module(s) of anti-malware programs - a part that runs all the time scanning for suspicious activity - will interfere with the proper installation of third party software, or major Microsoft updates that cannot be installed automatically by Automatic Update, the software will not install properly, and you may get no indication of that at all while installing the software.
To avoid that possibility, you should always DISABLE the resident module(s) of anti-malware programs, BEFORE you install third party software (software other than most Microsoft Updates, etc., that did not come with Windows ), especially when it's a major or complicated software package.
E.g. if you are using the free or paid version of AVG, you should disable the Resident Shield in AVG's 's settings in Windows (in AVG 2012 that's done under the title AntiVirus). In Norton (Symantec) products, there may be several things you need to disable, or set so they don't load for a specific short amount of time.
If you don't know how to do that, tell us which anti-malware software you are using.
When you are sure the software has installed correctly, re-enable the resident module(s).
That is especially important when you install the SP2 or SP3 Windows updates !
If you have a Norton (Symantec) anti-malware product installed, you probably MUST un-install it before you install the SP3 updates because it's resident module(s) can't be disabled so they're disabled until you enable them again. (You can only disable them for xx minutes- they're auto enabled when Windows is Restarted. After the SP3 updates have been installed , the first time you Restart Wnidows after that, the SP3 updates finish installing while loading Windows.)
Also, if IE 7 or 8 has already been installed, I recommend that you un-install that just before you install the SP3 updates, because if anything goes wrong with IE 7 or 8 after the SP3 updates have been installed, you CANNOT un-install the IE 7 or 8 version. If you install IE 7 or 8 after the SP3 updates have been installed, you can un-install it if you need to.