This file has been reported to be part of a spyware/malware/trojan. It is likely that the problem you are experiencing is linked directly to the spyware/malware/trojan rather than an actual missing DLL-file and the recommended course of action is to first locate/remove the Malware. We do not recommend downloading this file.
DLL-Files.com Support says:
STLB2.DLL is part of an AdWare called BrowserAid.
Here's a manual solution for you 'handyman-fixers' out there: (at your own risk)
DLL-files.com strongly recommends that you back up the registry before making
any changes to it. Incorrect changes to the registry can result in permanent
data loss or corrupted files.
1. Click start, choose 'run'
2. Type 'regedit' and press 'OK'
3. Navigate to and delete the following registry keys, if present:
HKEY_CLASSES_ROOT\AppID\{418B46A9-5343-4E1A-A654-42B04E3F869E}
HKEY_CLASSES_ROOT\AppID\{87690003-2714-45E7-8A1B-DC0658DE778C}
HKEY_CLASSES_ROOT\CLSID\{087173EF-9829-4F49-8340-A524177D3F60}
HKEY_CLASSES_ROOT\CLSID\{0ddbb570-0396-44c9-986a-8f6f61a51c2f}
HKEY_CLASSES_ROOT\CLSID\{12EE7A5E-0674-42f9-A76A-000000004D00}
HKEY_CLASSES_ROOT\CLSID\{12EE7A5E-0674-42f9-A76B-000000004D00}
HKEY_CLASSES_ROOT\CLSID\{337D0C1D-4053-4FAB-AF2B-45C2F7B0FAA6}
HKEY_CLASSES_ROOT\CLSID\{5F5564AC-DE7A-4DCD-9296-32E71A35DCB6}
HKEY_CLASSES_ROOT\CLSID\{606220AE-90E0-41CA-BF6D-C89272ED680C}
HKEY_CLASSES_ROOT\CLSID\{80672997-D58C-4190-9843-C6C61AF8FE97}
HKEY_CLASSES_ROOT\CLSID\{DBD7AAA2-1725-4663-8C8B-52A840693469}
HKEY_CLASSES_ROOT\CLSID\{E004800A-73C6-4587-B855-98D0CE0C16B1}
HKEY_CLASSES_ROOT\CLSID\{F20AE630-6DE2-43CA-A988-7CD40C36EF0B}
HKEY_CLASSES_ROOT\Interface\{2A167E61-D100-450D-A1B0-6EAF394BCB87}
HKEY_CLASSES_ROOT\Interface\{4A2563C7-FC68-4EE8-A11C-2022EBCC1B0F}
HKEY_CLASSES_ROOT\Interface\{4B0FCEB7-8163-46EE-9EAF-85BD933D0A46}
HKEY_CLASSES_ROOT\Interface\{670801FD-C247-4E44-9424-69E5D77C6725}
HKEY_CLASSES_ROOT\Interface\{8A7D38BE-849D-478F-A7CF-55EC95722358}
HKEY_CLASSES_ROOT\Interface\{E58F4168-608C-45C2-9BFF-061229730B2E}
HKEY_CLASSES_ROOT\Interface\{EE06D877-386F-4A44-A9ED-75EB6C3E7E80}
HKEY_CLASSES_ROOT\Interface\{EE06D877-386F-4A44-A9ED-75EB6C3E7E81}
HKEY_CLASSES_ROOT\Interface\{F8D96098-E9F7-42E1-88F3-A3719D70EA8D}
HKEY_CLASSES_ROOT\TypeLib\{12EE7A5E-0674-42F9-A76C-000000004D00}
HKEY_CLASSES_ROOT\TypeLib\{7313BFD0-62C4-40F4-8041-3FBDBC80AC07}
HKEY_CLASSES_ROOT\TypeLib\{85C2C2A1-3F20-4EAD-ADC3-BD3217391543}
HKEY_CLASSES_ROOT\TypeLib\{BA87B15B-7DE7-4DA4-8BF7-5C616D6C99DA}
HKEY_CLASSES_ROOT\bho.FResultsRequest
HKEY_CLASSES_ROOT\bho.FResultsRequest.1
HKEY_CLASSES_ROOT\Bho.FeaturedResultsBHO
HKEY_CLASSES_ROOT\Bho.FeaturedResultsBHO.1
HKEY_CLASSES_ROOT\bho.FResultsRequestDispatcher
HKEY_CLASSES_ROOT\bho.FResultsRequestDispatcher.1
HKEY_CLASSES_ROOT\bho.IAdvertisementBHO
HKEY_CLASSES_ROOT\bho.IAdvertisementBHO.1
HKEY_CLASSES_ROOT\AppID\bho.DLL
HKEY_CLASSES_ROOT\AppID\My404.DLL
HKEY_CLASSES_ROOT\My404.Bho404
HKEY_CLASSES_ROOT\My404.Bho404.1
HKEY_CLASSES_ROOT\_ATL_GENERATED.SearchToolbarBHO
HKEY_CLASSES_ROOT\_ATL_GENERATED.SearchToolbarBHO.1
HKEY_CLASSES_ROOT\_ATL_GENERATED.SearchToolbarName
HKEY_CLASSES_ROOT\_ATL_GENERATED.SearchToolbarName.1
HKEY_CLASSES_ROOT\BrowserAidToolbar.Helper
HKEY_CLASSES_ROOT\BrowserAidToolbar.Helper.1
HKEY_CLASSES_ROOT\BrowserAidToolbar.IEShower
HKEY_CLASSES_ROOT\BrowserAidToolbar.IEShower.1
HKEY_CLASSES_ROOT\BrowserAidToolbar.IEToolBar
HKEY_CLASSES_ROOT\BrowserAidToolbar.IEToolBar.1
HKEY_LOCAL_MACHINE\Software\Microsoft\Windows\Currentversion\Explorer\Browser Helper Objects\{087173ef-9829-4f49-8340-a524177d3f60}
HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Explorer\Browser Helper Objects\{0DDBB570-0396-44C9-986A-8F6F61A51C2F}
HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Explorer\Browser Helper Objects\{12EE7A5E-0674-42f9-A76A-000000004D00}
HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Explorer\Browser Helper Objects\{5F5564AC-DE7A-4DCD-9296-32E71A35DCB6}
HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Explorer\Browser Helper Objects\{80672997-D58C-4190-9843-C6C61AF8FE97}
HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Internet Explorer\Extensions\{07B7F771-1B8E-4B7B-823E-FFAC1732AA9E}
HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Internet Explorer\Explorer Bars\{12EE7A5E-0674-42f9-A76B-000000004D00}
HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Uninstall\LetsSearch
HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\RunWindowsUpdate
HKEY_CURRENT_USER\Software\A70F6A1D-0195-42a2-934C-D8AC0F7C08EB
HKEY_CURRENT_USER\Software\{12EE7A5E-0674-42f9-A76B-000000004D00}
4. Navigate to the registry subkey:
HKEY_LOCAL_MACHINE\Software\Microsoft\Windows\CurrentVersion\Run
5. In the right pane, delete any of the following values, if they exist:
"{12EE7A5E-0674-42f9-A76B-000000004D00}" = "rundll32.exe stlb2.dll,DllRunMain"
"A70F6A1D-0195-42A2-934C-D8AC0F7C08EB" = "rundll32.exe E6F1873B.DLL, D9EBC318C"
"Rundll32_7" = "rundll32.exe C:\WINDOWS\System32\msiefr40.dll,DllRunServer"
"Rundll32_8" = "rundll32.exe C:\1.dll,DllRunServer"
6. Navigate to the following registry key:
HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Internet Explorer\Toolbar
7. In the right pane, delete the value:
"{12EE7A5E-0674-42f9-A76B-000000004D00}" = ""
8. Exit the Registry Editor.
9. Reboot your computer
Note: Malwarebytes Anti Malware has been repoted to kill this one for you as well, without the hassle!