We have to face many problems in the initial stage of moving from one version to another version.
Some times your application working smoothly in iis6 will not work on IIS7.
There may be one or many reasons of such problem. In such condition first of all check these things on your machine.
1) Whether or not asp.net installed on your machine.
Go to Control panel -> add remove windows component -> Expand Internet information server Select asp.net.
2) Check Application pool:
iis7 have two mode of operation
a) Classic-Pipeline mode.
b) Integrated -Pipeline mode
if your application have any code in Global Application file(Global.asax) . that is necessary to execute first (URL rewriting). configure application to use Classic pipeline mode.
3)Check all modules in iis7 are assigned according to type of resource.
Page handler not mapped :Dynamic(aspx) Pages will not server by IIS.
for more detail on iis please visit about setting up iis visit