diff --git a/BizHawk.Common/Util.cs b/BizHawk.Common/Util.cs
index e7981c80db..1fef4d6827 100644
--- a/BizHawk.Common/Util.cs
+++ b/BizHawk.Common/Util.cs
@@ -22,7 +22,7 @@ namespace BizHawk.Common
 		{
 			using (var md5 = System.Security.Cryptography.MD5.Create())
 			{
-				md5.TransformFinalBlock(data, offset, len);
+				md5.ComputeHash(data, offset, len);
 				return BytesToHexString(md5.Hash);
 			}
 		}
@@ -36,7 +36,7 @@ namespace BizHawk.Common
 		{
 			using (var sha1 = System.Security.Cryptography.SHA1.Create())
 			{
-				sha1.TransformFinalBlock(data, offset, len);
+				sha1.ComputeHash(data, offset, len);
 				return BytesToHexString(sha1.Hash);
 			}
 		}
diff --git a/BizHawk.Emulation.Cores/Consoles/Sega/gpgx/GPGX.cs b/BizHawk.Emulation.Cores/Consoles/Sega/gpgx/GPGX.cs
index e45a570828..960f9932ba 100644
--- a/BizHawk.Emulation.Cores/Consoles/Sega/gpgx/GPGX.cs
+++ b/BizHawk.Emulation.Cores/Consoles/Sega/gpgx/GPGX.cs
@@ -49,6 +49,10 @@ namespace BizHawk.Emulation.Cores.Consoles.Sega.gpgx
 
 			//hack, don't use
 			//romfile = File.ReadAllBytes(@"D:\encodes\bizhawksrc\output\SANIC CD\PierSolar (E).bin");
+			if (romfile != null && romfile.Length > 16 * 1024 * 1024)
+			{
+				throw new InvalidOperationException("ROM too big!  Did you try to load a CD as a ROM?");
+			}
 
 			try
 			{