In your case the Download Manager is facing difficulty in accessing internet due to a third party software (remnant) might be.
Could you provide some information like;
Were you using any other security software in the computer ?
What is the type of internet connection for the computer ?
Assuming you have no other antivirus software and your internet explorer not configured to a proxy setting .
Here are a few steps you can try.
Option 1 - Reset the System Clock
Verify the system date on your computer by double-clicking the clock in your system tray. When the Date and Time Properties window opens, confirm the date, time, and time zone are correct. If they are not correct, adjust them in this order:
1. Time Zone
To get an accurate time, you can use web-based world time pages. You may wish to check the time periodicallyto ensure proper synchrinization, especially after the computer is turned off for a length of time. You may need a new clock battery if your system does not keep accurate time. Please consult your computer manufacturer for assistance.
Modify the Internet Options setting to use SSL 3.0
1. Close any open Internet Explorer windows.
2. Click Start, Control Panel.
3. Double-click Internet Options.
4. Select the Advanced tab.
5. Scroll down to the end of the list and select Use SSL 3.0.
6. Click Apply.
7. Click OK.
8. Restart the installation.
Option 3 - Disable the option for Internet Explorer to check for server Certificate revocation
IMPORTANT: The workaround below is only temporary. It must be reversed after successful installation.
1. Click Start, All Programs, Internet Explorer.
2. Click Tools, Internet Options.
3. Select the Advanced Tab.
4. Navigate to the security section and deselect Check for server Certificate revocation.
5. Click Apply to save the changes and test.
Merry christmas !!!