Help Apps installation problem

[siamrumi]

I am using HTC Desire and updated it to Android 2.2 with out rooting. After the update everything seems fine except the apps instalation issue. I have tried to download apps from Android Market and after downloading the apps starts to install automaticly, just after installation begins my phone reboots. I have tried it several time but every time I am failed and returned with this sick problem....Please help me out....

 

[childlike]

I have same problem.

 

[lekky]

it happens when you try and install just one app, or when you try to install multiple at the same time?

 

[Medea]

i have HTC desire z and some application that I tried to download is giving me error 18. How can I fix it?