When I was trying to install some plugins, I got an error massage like this:
Downloading install package from ******.zip
Unpacking the package.
Parse error: syntax error, unexpected $end in ***/wp-admin/includes/class-pclzip.php on line 4128
It seems that the wordpress that I used can not cope with the zip file. So I tried to download and unzip the zip manually. After the extractd files were uploaded, the plugin was found in the plugin list and is available to be activated.
This is not a good solution because I would need to do a lot of extra work to enable a single plugin. Then I googled it and found that a number of people is suffering the same problem and almost no one's got the solution.
Therefore I made a small attempt copying the class-pclzip.php file from wordpress 2.9 and replaced the same file in 3.0.1. That did the trick and now every thing seems to be alright.
I guess there might be someone else who is having the same problem and hope that this post may offer a little help.