ma has this listed as a common but on their FAQ page, it sais to go into (win7) users, username, appdata, local, temp and delete the entropia folder and/or its contents. you have to go into folder options and show hidden files to see 'appdata' though. i'll go test now and see if it works for me. [edit: it didn't work, but i found a fix]
I was able to get it to work. For me, the following fixed the access denied and etc errors, inability to clear cache in cl, inability to repair installation, inability to download content, inability to load the game. Lol, MA seriously better get it together because probably loads of new players are quitting before they even begin when they encounter this problem! To download the content, I didn't need to load as admin (this creates problems with my controller and screenshot apps etc anyways, needing to also be loaded as admin etc). MA's main website sais to turn off UAC in order to download content, and then to restore it to how you had if afterwards. That's not a big deal to me since I only have to install EU on a fresh installation of Windows anyways. Here's how I got it ALL to work after encountering every roadblock.
for windows 7 64bit:
1st) Control Panel > User Accounts > Change User Account Control (UAC) Settings. Select "Never Notify" and click ok. Reboot Computer.
2nd) Open Client Loader and let it download all the content. Remember sometimes it unchecks all the content selections you chose so double check that if you think it's all done.
3rd) Go back to the User Account Settings and put them back where you want them. Reboot Computer again.
4th) Right Click the "Entropia Universe" Client Loader Icon in your Start Menu or on your Desktop and click on "Properties". Click the "Compatibility" tab. Select "Run this program in compatibility mode for:" and select "Windows XP (Service Pack 3)". For me, this option was already selected once i clicked to select the "Run this etc" box. And, yes, even though you are using windows 7 you are selecting 'xp sp3'. Selecting Windows 7 on this list won't fix the problem).
For me, this fixed the access denied and etc errors, inability to clear cache in cl, inability to repair installation, inability to download content, inability to load the game. Lol, MA seriously better get it together because probably loads of new players are quitting before they even begin when they encounter this problem!