Trouble Authorizing my PC

Question

I need to transfer my applications and data from my ipod touch to iTunes on my PC. This computer was used before to synchronize somebodies else's iphone to itunes using a different Apple account name.  I used to synch. my iTouch to a laptop, but not anymore, and now, trying to use this PC as my personal iTines reference, I am afraid to loose my applications and data if I dont Transfer purchases to iTunes in the new PC.
Every time when I try to transfer purchases from my itouch to the new PC a msg pops out saying that I have to authorize this PC to be used by my Apple account name. I Authorize it, and after that when I try to transfer purchases again, it asks to authorize again, and says that this computer is no longer authorized.  I repeat the process over and over many times but it keeps doing the same thing and put in a loop of authorizing and then trying to trasfere purchases and discovering that I need to authorize again.
Help me please

Answer 1

Thank you for you answer, I tried the first and the second options mentioned in the page you sent.
I still have the same problem. I am going to tell you the full pictures now, and I will be very thankful, because I am not that fully aware of how Synchronizing with iTunes really works.
Now .. when I bought my iTouch I used my uncle apple user name because I didnt have a credit card. I was using my laptop to synch. that iTouch to iTune, and I had no trouble at all. All the purchased apps where purchased using that Apple account name. Today I tried to synch. my iTouch to iTunes in a new PC using the same old Apple account. A message appeared saying that this account has been used to authorize 5 computers and can not be used to aouthorize any other computer unless you deauthorize one of the old five ones.
I said I am going to have a new start and I created a new Apple account. Now I attached my iTouch to the PC and tried to synch. with iTunes. Before doig that a msg appeared saying that I have to transfer the already purchased apps on my iTouch to iTunes because if I dont do that I will loose all my applications. Okay I didnt Synchronize and instead I authorized the computer. It tells me after that " you have authorized 1 out of 5 computers using your account" , okay cool .. now I go to " File > Transfere Purchases from iPod " and I choose it. After that a msg appears saying : " This computer is no longer authorized for apps that are installed on iPod, would you like to authorize this computer for items purchased from the iTunes store? , if you don't authorize, all your apps and their data will be deleted from iPod " , this is the complete msg.
I dont know what to do ... I mean if I go for it and synchronize I am afraid that I am foing to loose my apps. They say that I have to authorize all my accounts. The old account I used is no longer allowed to authorize an extra computer. What should I do ?