HP laptop/Windows Mail Vista/Mozilla Recently I am unable to open attachments that I receive with email through my Windows Mail in Vista. Not sure if I disabled something or not.

Sounds like a firewall problem. of antivirus has blocked it.
try turning off windows firewall and antivirus and test the mail.
You could also try the Server authentication settings on the mail accounts.

look at IE Tools
is Work offline is it ticked? if so untick it
Make sure that the default browser is IE.

Open Internet Explorer browser.
From the menu bar, click File. (If menu is not shown, press "Alt" + F button on your keyboard)
Uncheck "Work offline" by clicking on it.

hmm that is part of the email application that you are using some of them need a bit of time to find the file and attach them usually showing a progress bar while attachment is done

what email reader are you using?

are you trying to transfer Windows mail to Thunderbird OR thunderbird to Windows Mail?

• Thunderbird http://kb.mozillazine.org/Importing_and_exporting_your_mail
• Window Mail http://email.about.com/od/mozillathunderbirdtips/qt/et_export_to_oe.htm
• 
  

change you browser to Mozilla Firefox ,u can download it free from www.mozilla.com,

Please try to delete all cookies and clear all cache. Follow the steps provided below.

Internet Explorer :
1. Open Internet explorer > Tools > Internet Option
2. On the General Tab under Browsing History, click on Delete
3. On the pop up windows that opens, make sure all check box are checked that has cookies, temporary files, and etc..., then click on delete
4. Just close and re-open Internet Explorer

Mozilla Firefox
1. Open Mozilla Firefox > Tools > Clear Private data
2. On the pop up windows, make sure all boxes are checked as well and click on delete.
3. Close and reopen Mozilla Firefox.

Probable cause is the explorer add-ons, i recommend you to use mozilla.

1. click on compose
2. go to attach
3. select document
4. click on attach
5. send to desired email-id

I would scan whatever it is and then save it as a picture or whatever you choose and send it as a normal attached file.

If you use Yahoo! Mail for all your email needs, some of the amenities of Windows seem to elude you. A click on an email link in your browser brings up Outlook Express or another desktop email program, not a new message in Yahoo! Mail. Trying to send a file directly from Word, OpenOffice.org or another office application yields the same, unsatisfactory result.

Fortunately, the state of dissatisfaction need not be permanent. It will be overcome by making Yahoo! Mail act as your default email program in Windows, which, if you use Windows 95 or later is an easy thing to do.
Make Yahoo! Mail Your Default Windows Email Program

To set up Yahoo! Mail as your default email client in Windows:

* Download and install Yahoo! Messenger.
* Select Tools | Internet Options... from the menu in Internet Explorer.
* Go to the Programs tab.
* Make sure Yahoo! Mail is selected under E-mail.
* Click OK.

Yahoo! as Default Email: Does Not Work under Windows Vista

Unfortunately, Yahoo! Mail as your default email program may be hard-wired to use Internet Explorer instead of your default browser, and it does not work in Windows Vista.
Make Yahoo! Mail the Default Email Composer in Mozilla Firefox

In Mozilla Firefox, you can turn to the Mailto 2 Webmail script for Greasemonkey to have Yahoo! Mail handle email links (even under Windows Vista).

http://email.about.com/od/yahoomailtips/qt/et_default_mail.htm