I can access this site with my ID but cannot attach to project with it after dl of boinc 4.45 for windows

What error message are you getting?

Make sure you are not putting spaces at the front or rear of the URL and the ACCT/PW.
<a href="http://boinc-doc.net/boinc-wiki/index.php?title=Main_Page">Link to Unoffical Wiki for BOINC, by Paul and Friends</a>

The master page is down so the project client doesn't know where to find the scheduler.

If you still have some old account_climateprediction.net.xml you can put it into your BOINC folder and restart BOINC.

You could create such an XML filefrom scatch orfrom any other account XML file with notepad, vi or so, it is a plain text file like this :

&lt;account&gt;
&lt;master_url&gt;http://climateprediction.net/&lt;/master_url&gt;
&lt;authenticator&gt;1234567890abcdef1234567890abcdef&lt;/authenticator&gt;
&lt;project_name&gt;climateprediction.net&lt;/project_name&gt;
&lt;project_preferences&gt;
&lt;resource_share&gt;100&lt;/resource_share&gt;
&lt;project_specific&gt;
&lt;color_scheme&gt;Tahiti Sunset&lt;/color_scheme&gt;
&lt;name_old&gt;&lt;/name_old&gt;
&lt;/project_specific&gt;
&lt;/project_preferences&gt;
&lt;/account&gt;

Your account ID goes into the authenticator line.