Trouble on first generation iPhone to 2.02 update version

Hi, I updated my first generation Iphone to the 2.02 update version.
This has developed a serious problem to my phone. Since then, I am no longer able to install new apps on my phone.
If something requires that I delete the previous version to be able to install the apps.
How can I rectify this problem because it is causing a lot of inconveniences to me?
Please help.

Some of the applications in your iTunes library were not installed on the iPhone ‘Kevin Pedraja's iPhone” because one or more errors occurred.
For a list of applications that could not be installed, click below.
3 total warnings
Some of the applications in your iTunes library were not in…
For a list of applications that could not be installed, click below.
The application "Cro-Mag was not installed on the iPhone.,.
The application "Thlngs” was not installed on the iPhone s…
