Laptop tends to hang on Win 7 logo on boot.

There are a few things you can start looking at. The system tools Check Disk and System File Checker as well as looking over the msconfig's Start items tab and any unnecessary 3rd party background services depending on what programs you have on would be a start.

Disk errors would be fixed(errors on drive not failing drive) with the Disk Check tool, chkdsk /r at command prompt or click the Check now button when right clicking on the hard drive's icon in WE and opening the Tools tab to schedule that for the next startup. Note especially after any number of hard boots or forced shutdowns to deal with the likely errors then created on top of the original problem.

The reduction of startup items in the msconfig is also one way to isolate a program where something doesn't want to load up normally on each startup. If a program is the source by narrowing what loads up along with Windows will eventually isolate that program when suddenly noticing everything is back to normal.

The System File Checker also can play a role and why that is included, sfc /scannow at the Start>Run command line to get that going, since it will verfy all main files are present and replace any found corrupt or missing. When a system file gets a little shaky and flaky it's time to...

The last other item getting back to startups of course would be device and software drivers as a possible culprit to include there. A driver sticking too often the graphics drivers as the usual villian will tend to see Windows hang up when starting and first going to load drivers into memory and one tries to load sideways where it doesn't belong like a system reserved memory address can eventually lead to those dreaded BSOD "Blues"!

The other alternative method to get past a hang up when starting up would be booting up in Safe mode to run the msconfig utility. You would go into the Startup tab to look over all unnecessary items to see those unchecked as well as a review of the Services tab once you check off the "hide all microsoft services" box before entering to only show 3rd party services which can be started up manually.

By reducing the number of startup even disabling all startup items only re-enabling one at time the time consuming process will usually reveal a program like the ATI Mobiliy Catalyst or for your laptop model the NVidia GeForce GT 425M driver set or other offender preventing a normal startup. The Startup repair tool can also be a large help at times but for main system files not for 3rd party items which may be corrupted.

The first thing to come to mind however would be nuking the graphics driver set right off once you have a fresh download of the latest update onhand to reinstall fresh. That will either confirm or rule out video drivers as the cause.

Often a driver gets a little tainted and starts loading sideways on you and why you end up seeing Windows start hanging when going to start up. The logo screen is right about the time the initial load of all device drivers into memory takes place immediately following the post tests and the hardware detection process begins.

The safe mode method however while taking some time to go through things is generally the sure fire method if it turns out to be something other then any drivers however. A program install going bad or some type of malware not being ruled out is another factor. You would notice a virus like an I-Worm however since you would find the desktop unusable over simply not arriving at the desktop.