Psp say "the copyright protection information is invalid"

It depends what firmware you are trying to upgrade to. If you want to install custom firmware on your PSP, check this YouTube channel:
http://www.youtube.com/user/ubeenstryked
If you want to install official firmware, you can find a list of downloads here: http://downloads.exophase.com/category/psp-official-firmware/
When you select the firmware you want to install, download it. You will get a .zip file with a file inside called EBOOT.PBP. Follow these steps to update:
1.) Connect your PSP to your PC. 2.) Open the PSP folder and then the GAME folder. 3.) Right click INSIDE the GAME folder, and click New Folder 4.) Name the new folder UPDATE 5.) Place the EBOOT.PBP file you downloaded into the UPDATE folder. 6.) Disconnect your PSP from your computer, and select the MEMORY STICK ICON in the GAME section. 7.) Find the PSP Update Version.. and run it, complete the on screen steps to install the new firmware.

first you need custom firmware to play iso files, second the psx2psp is to change playstation 1 games into psp eboots not psp games, the iso is all you need for psp games if you have custom firmware, you just need to create a folder called ISO in the root of your memory stick and put the iso files in there

1. To get firmware upgrade data . you need to download a file form PSP official website http://us.playstation.com/psp/downloads/systemupdate . File name is EBOOT.PBP ..
2. connect your pc with psp . now move to the settings and the secound option from the top press X .
3. Now click the removable disk and there would be a foldr name PSP , inside it there is another folder GAME . inside it create another folder name it as update . now paste EBOOT.PBP in that folder
4. Remove your PSP
5. On your PSP press "X" on *.**, which means an update . just install it on your psp

You just connect the psp to your computer using a usb cable.Then create a folder in your Memory Stick Duo named “PSP“, under this folder, create a sub-folder named “GAME“, under this sub-folder, create another sub-folder named “UPDATE” (Note: all folders name must be CAPITALIZED).Download the PSP 5.51 update file via this link: http://du01.psp.update.playstation.org/update/psp/image/us/2009_0611_148d2a024741df54eacabbc79d9f3014/EBOOT.PBP.Save the file as “EBOOT.PBP” to your desktop then inside the UPDATE folder copy the EBOOT.PBP.Then go to games>memory stick and hit the x button there should be an game press x again to upgrade.The udpate process will take about 10 minutes.Thats all.

if that psx game is on eboot.pbp file.put it on GAME FOlder if your running a lower version of custom firmware put it on GAME150 folder

You will need a emulator or if you have downloaded the ps1 game of sony themselves for psp contact them to get your money back

yes you can if you have a custom firmware. the psp will not recognize the eboot file itself unless you put the eboot file inside of a folder with the name of the game as the folder name. then you save it to psp/game. iso and cso files are placed in the iso folder of the root.

I think you are trying to install a CFW update on an OFW PSP. Just rename 401.PBP to EBOOT.PBP and get rid of the other EBOOT.PBP.

You need to put the whole folder with the EBOOT.PBP and the KEYS.BIN in it, in the GAME folder. Before that I would upgrade to M-33 custom firmware.

Ok, the PSP emulator is a program that emulates the work of PSP on your computer, and take a portion of your PC's CPU to emulate the PSP's Processor. Or you can say it's a program that runs your PSP games through a window. To Run your "Doom on PSP" I can paste some text from the readme.txt inside this file: http://psp-news.dcemu.co.uk/files/doompspv005plus.zip Release Notes for Doom-PSP 0.05 plus: To Install fw 1.0 and 2.0(with loader) 1. Create Doom dir under Games. 2. Copy save, wads, inst, config.ini, and timidity.cfg into doom folder. 3. copy eboot.pbp from fw10 into doom dir. 4. copy any main wads into doom/wads dir and pwads into doom/wads/pwads dir. 5. launch game, select wads and play! to set up controls press L+R+Start and follow instructions. fw 1.5 1. Create Doom dir under Games. 2. Create Doom% dir under Games. 2. Copy save, wads, inst, config.ini, and timidity.cfg into doom folder. 3. copy eboot.pbp from fw15/Doom into doom dir. 5. copy eboot.pbp from fw15/Doom% into doom% dir. 4. copy any main wads into doom/wads dir and pwads into doom/wads/pwads dir. 5. launch game, select wads and play! to set up controls press L+R+Start and follow instructions. Then give us feedback. Play nice with your PSP. Goodluck