Dear chaser,
If you have a decent internet speed and able to re-download grandchase files in less than 30mins, I don't really see a point for you to continue reading this... Just download GC from Steam in regular way

As title said, you don't have to redownload whole 3.7gb file from Steam. Downloading 3.7gb data is a real pain for those who have a download speed of 100kbps or slower (even w/ 1mbps it still take you approximate 1 hour, lolz)
Note that you still have to download about hundred-ish mb data (Steam folder and some unique data file of Steam GC)

So what to do? Throw a pokeball, or Run? Neither lol

1. Download & Install Steam
2. Open your Steam folder (It should be in C: drive by default), then go to SteamApps\common, create a new folder and rename it into Grand Chase
3. Copy and paste all your GC file into the newly created Grand Chase folder
4. Search Grand Chase on Steam, click Playnow and forward to installation step
5. Steam will detect the existance of your GC folder before it start downloading and will take awhile to verify the folder.

After verify, you will see GC downloading process, 3.6gb/3.7gb downloaded.
Save your time on not downloading 3.6gb datas.

IE issue

Although you can update your IE, reinstall or doing something blahblahblah, but I don't see a point when this can be solve by an alternate method.

If IE pop out but can't show you to linking page :
1. Right Click the IE, Create an shortcut in desktop
2. Run the shortcut
2a. Assume If you have other browser set as your default browser, it will work fine with this way.
2b. If the page still open with IE and not some other browser: Right click the shortcut properties, then click on 2nd tab, copy the URL. Then paste and go on another browser