SD with problems?

I have a Sandisk class 10 SDHC card U1 Extreme 45MB / s 32GB to use for recording HD video, and lately I am having problems artifacts in the video image.
I suspect it may be a problem of the sd card.
I’ve tested with h2testw and this is the result that has given me:

The media is likely to be defective.
29.7 GByte OK (62304830 sectors)
1.7 MByte DATA LOST (3522 sectors)
Details:0 KByte overwritten (0 sectors)
1.7 MByte slightly changed (< 8 bit/sector, 3522 sectors)
0 KByte corrupted (0 sectors)
0 KByte aliased memory (0 sectors)
First error at offset: 0x00000000004cb2b0
Expected: 0xbb945fe1ed925fb0
Found: 0xbb945fe1ed925fbf
H2testw version 1.3
Writing speed: 19.5 MByte/s
Reading speed: 25.4 MByte/s
H2testw v1.4

Hello,

You can try to format the card with the computer also and see if the card is still having issues. Then you shall check if this card is recommended for your camera and if you are sure that its compatible and the format does not resolve the issue, then you shall contact the support of sandisk to request a replacement.

Yesterday i did another test with H2testw , this time with a netbook Intel Atom N450 1.66 GHz 1 GB RAM using the built-in card reader 2.0 (the first time I did it with a computer tower mounted I7 4770K 16Gb of RAM and a card reader 3.0 coolbox CR- ​​430, although the card reader is 2.0).
It took longer than the first time and reading speed was much lower , but did not give me any error in the card.

Should definitely be a problem with the card reader.
I bought an external reader I put it in the I7 and does not leave me any error.

This is the final result of the test:

Test finished without errors.
You can now delete the test files *.h2w or verify them again.
Writing speed: 24.4 MByte/s
Reading speed: 27.1 MByte/s
H2testw v1.4

This is strange , it is the first time i encounter this kind of problem .